what is the thesis of nurture

Nature vs. Nurture Debate In Psychology

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

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BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

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The nature vs. nurture debate in psychology concerns the relative importance of an individual’s innate qualities (nature) versus personal experiences (nurture) in determining or causing individual differences in physical and behavioral traits. While early theories favored one factor over the other, contemporary views recognize a complex interplay between genes and environment in shaping behavior and development.

Key Takeaways

• Nature is what we think of as pre-wiring and is influenced by genetic inheritance and other biological factors.
• Nurture is generally taken as the influence of external factors after conception, e.g., the product of exposure, life experiences, and learning on an individual.
• Behavioral genetics has enabled psychology to quantify the relative contribution of nature and nurture concerning specific psychological traits.
• Instead of defending extreme nativist or nurturist views, most psychological researchers are now interested in investigating how nature and nurture interact in a host of qualitatively different ways.
• For example, epigenetics is an emerging area of research that shows how environmental influences affect the expression of genes.

The nature-nurture debate is concerned with the relative contribution that both influences make to human behavior, such as personality, cognitive traits, temperament and psychopathology.

Examples of Nature vs. Nurture

Nature vs. nurture in child development.

In child development, the nature vs. nurture debate is evident in the study of language acquisition . Researchers like Chomsky (1957) argue that humans are born with an innate capacity for language (nature), known as universal grammar, suggesting that genetics play a significant role in language development.

Conversely, the behaviorist perspective, exemplified by Skinner (1957), emphasizes the role of environmental reinforcement and learning (nurture) in language acquisition.

Twin studies have provided valuable insights into this debate, demonstrating that identical twins raised apart may share linguistic similarities despite different environments, suggesting a strong genetic influence (Bouchard, 1979)

However, environmental factors, such as exposure to language-rich environments, also play a crucial role in language development, highlighting the intricate interplay between nature and nurture in child development.

Nature vs. Nurture in Personality Development

The nature vs. nurture debate in personality psychology centers on the origins of personality traits. Twin studies have shown that identical twins reared apart tend to have more similar personalities than fraternal twins, indicating a genetic component to personality (Bouchard, 1994).

However, environmental factors, such as parenting styles, cultural influences, and life experiences, also shape personality.

For example, research by Caspi et al. (2003) demonstrated that a particular gene (MAOA) can interact with childhood maltreatment to increase the risk of aggressive behavior in adulthood.

This highlights that genetic predispositions and environmental factors contribute to personality development, and their interaction is complex and multifaceted.

Nature vs. Nurture in Mental Illness Development

The nature vs. nurture debate in mental health explores the etiology of depression. Genetic studies have identified specific genes associated with an increased vulnerability to depression, indicating a genetic component (Sullivan et al., 2000).

However, environmental factors, such as adverse life events and chronic stress during childhood, also play a significant role in the development of depressive disorders (Dube et al.., 2002; Keller et al., 2007)

The diathesis-stress model posits that individuals inherit a genetic predisposition (diathesis) to a disorder, which is then activated or exacerbated by environmental stressors (Monroe & Simons, 1991).

This model illustrates how nature and nurture interact to influence mental health outcomes.

Nature vs. Nurture of Intelligence

The nature vs. nurture debate in intelligence examines the relative contributions of genetic and environmental factors to cognitive abilities.

Intelligence is highly heritable, with about 50% of variance in IQ attributed to genetic factors, based on studies of twins, adoptees, and families (Plomin & Spinath, 2004).

Heritability of intelligence increases with age, from about 20% in infancy to as high as 80% in adulthood, suggesting amplifying effects of genes over time.

However, environmental influences, such as access to quality education and stimulating environments, also significantly impact intelligence.

Shared environmental influences like family background are more influential in childhood, whereas non-shared experiences are more important later in life.

Research by Flynn (1987) showed that average IQ scores have increased over generations, suggesting that environmental improvements, known as the Flynn effect , can lead to substantial gains in cognitive abilities.

Molecular genetics provides tools to identify specific genes and understand their pathways and interactions. However, progress has been slow for complex traits like intelligence. Identified genes have small effect sizes (Plomin & Spinath, 2004).

Overall, intelligence results from complex interplay between genes and environment over development. Molecular genetics offers promise to clarify these mechanisms. The nature vs nurture debate is outdated – both play key roles.

Nativism (Extreme Nature Position)

It has long been known that certain physical characteristics are biologically determined by genetic inheritance.

Color of eyes, straight or curly hair, pigmentation of the skin, and certain diseases (such as Huntingdon’s chorea) are all a function of the genes we inherit.

These facts have led many to speculate as to whether psychological characteristics such as behavioral tendencies, personality attributes, and mental abilities are also “wired in” before we are even born.

Those who adopt an extreme hereditary position are known as nativists.  Their basic assumption is that the characteristics of the human species as a whole are a product of evolution and that individual differences are due to each person’s unique genetic code.

In general, the earlier a particular ability appears, the more likely it is to be under the influence of genetic factors. Estimates of genetic influence are called heritability.

Examples of extreme nature positions in psychology include Chomsky (1965), who proposed language is gained through the use of an innate language acquisition device. Another example of nature is Freud’s theory of aggression as being an innate drive (called Thanatos).

Characteristics and differences that are not observable at birth, but which emerge later in life, are regarded as the product of maturation. That is to say, we all have an inner “biological clock” which switches on (or off) types of behavior in a pre-programmed way.

The classic example of the way this affects our physical development are the bodily changes that occur in early adolescence at puberty.

However, nativists also argue that maturation governs the emergence of attachment in infancy , language acquisition , and even cognitive development .

Empiricism (Extreme Nurture Position)

At the other end of the spectrum are the environmentalists – also known as empiricists (not to be confused with the other empirical/scientific  approach ).

Their basic assumption is that at birth, the human mind is a tabula rasa (a blank slate) and that this is gradually “filled” as a result of experience (e.g., behaviorism ).

From this point of view, psychological characteristics and behavioral differences that emerge through infancy and childhood are the results of learning.  It is how you are brought up (nurture) that governs the psychologically significant aspects of child development and the concept of maturation applies only to the biological.

For example, Bandura’s (1977) social learning theory states that aggression is learned from the environment through observation and imitation. This is seen in his famous bobo doll experiment (Bandura, 1961).

Also, Skinner (1957) believed that language is learned from other people via behavior-shaping techniques.

Evidence for Nature

• Biological Approach
• Biology of Gender
• Medical Model

Freud (1905) stated that events in our childhood have a great influence on our adult lives, shaping our personality.

He thought that parenting is of primary importance to a child’s development , and the family as the most important feature of nurture was a common theme throughout twentieth-century psychology (which was dominated by environmentalists’ theories).

Behavioral Genetics

Researchers in the field of behavioral genetics study variation in behavior as it is affected by genes, which are the units of heredity passed down from parents to offspring.

“We now know that DNA differences are the major systematic source of psychological differences between us. Environmental effects are important but what we have learned in recent years is that they are mostly random – unsystematic and unstable – which means that we cannot do much about them.” Plomin (2018, xii)

Behavioral genetics has enabled psychology to quantify the relative contribution of nature and nurture with regard to specific psychological traits. One way to do this is to study relatives who share the same genes (nature) but a different environment (nurture). Adoption acts as a natural experiment which allows researchers to do this.

Empirical studies have consistently shown that adoptive children show greater resemblance to their biological parents, rather than their adoptive, or environmental parents (Plomin & DeFries, 1983; 1985).

Another way of studying heredity is by comparing the behavior of twins, who can either be identical (sharing the same genes) or non-identical (sharing 50% of genes). Like adoption studies, twin studies support the first rule of behavior genetics; that psychological traits are extremely heritable, about 50% on average.

The Twins in Early Development Study (TEDS) revealed correlations between twins on a range of behavioral traits, such as personality (empathy and hyperactivity) and components of reading such as phonetics (Haworth, Davis, Plomin, 2013; Oliver & Plomin, 2007; Trouton, Spinath, & Plomin, 2002).

Implications

Jenson (1969) found that the average I.Q. scores of black Americans were significantly lower than whites he went on to argue that genetic factors were mainly responsible – even going so far as to suggest that intelligence is 80% inherited.

The storm of controversy that developed around Jenson’s claims was not mainly due to logical and empirical weaknesses in his argument. It was more to do with the social and political implications that are often drawn from research that claims to demonstrate natural inequalities between social groups.

For many environmentalists, there is a barely disguised right-wing agenda behind the work of the behavioral geneticists.  In their view, part of the difference in the I.Q. scores of different ethnic groups are due to inbuilt biases in the methods of testing.

More fundamentally, they believe that differences in intellectual ability are a product of social inequalities in access to material resources and opportunities.  To put it simply children brought up in the ghetto tend to score lower on tests because they are denied the same life chances as more privileged members of society.

Now we can see why the nature-nurture debate has become such a hotly contested issue.  What begins as an attempt to understand the causes of behavioral differences often develops into a politically motivated dispute about distributive justice and power in society.

What’s more, this doesn’t only apply to the debate over I.Q.  It is equally relevant to the psychology of sex and gender , where the question of how much of the (alleged) differences in male and female behavior is due to biology and how much to culture is just as controversial.

Polygenic Inheritance

Rather than the presence or absence of single genes being the determining factor that accounts for psychological traits, behavioral genetics has demonstrated that multiple genes – often thousands, collectively contribute to specific behaviors.

Thus, psychological traits follow a polygenic mode of inheritance (as opposed to being determined by a single gene). Depression is a good example of a polygenic trait, which is thought to be influenced by around 1000 genes (Plomin, 2018).

This means a person with a lower number of these genes (under 500) would have a lower risk of experiencing depression than someone with a higher number.

The Nature of Nurture

Nurture assumes that correlations between environmental factors and psychological outcomes are caused environmentally. For example, how much parents read with their children and how well children learn to read appear to be related. Other examples include environmental stress and its effect on depression.

However, behavioral genetics argues that what look like environmental effects are to a large extent really a reflection of genetic differences (Plomin & Bergeman, 1991).

People select, modify and create environments correlated with their genetic disposition. This means that what sometimes appears to be an environmental influence (nurture) is a genetic influence (nature).

So, children that are genetically predisposed to be competent readers, will be happy to listen to their parents read them stories, and be more likely to encourage this interaction.

Interaction Effects

However, in recent years there has been a growing realization that the question of “how much” behavior is due to heredity and “how much” to the environment may itself be the wrong question.

Take intelligence as an example. Like almost all types of human behavior, it is a complex, many-sided phenomenon which reveals itself (or not!) in a great variety of ways.

The “how much” question assumes that psychological traits can all be expressed numerically and that the issue can be resolved in a quantitative manner.

Heritability statistics revealed by behavioral genetic studies have been criticized as meaningless, mainly because biologists have established that genes cannot influence development independently of environmental factors; genetic and nongenetic factors always cooperate to build traits. The reality is that nature and culture interact in a host of qualitatively different ways (Gottlieb, 2007; Johnston & Edwards, 2002).

Instead of defending extreme nativist or nurturist views, most psychological researchers are now interested in investigating how nature and nurture interact.

For example, in psychopathology , this means that both a genetic predisposition and an appropriate environmental trigger are required for a mental disorder to develop. For example, epigenetics state that environmental influences affect the expression of genes.

What is Epigenetics?

Epigenetics is the term used to describe inheritance by mechanisms other than through the DNA sequence of genes. For example, features of a person’s physical and social environment can effect which genes are switched-on, or “expressed”, rather than the DNA sequence of the genes themselves.

Stressors and memories can be passed through small RNA molecules to multiple generations of offspring in ways that meaningfully affect their behavior.

One such example is what is known as the Dutch Hunger Winter, during last year of the Second World War. What they found was that children who were in the womb during the famine experienced a life-long increase in their chances of developing various health problems compared to children conceived after the famine.

Epigenetic effects can sometimes be passed from one generation to the next, although the effects only seem to last for a few generations. There is some evidence that the effects of the Dutch Hunger Winter affected grandchildren of women who were pregnant during the famine.

Therefore, it makes more sense to say that the difference between two people’s behavior is mostly due to hereditary factors or mostly due to environmental factors.

This realization is especially important given the recent advances in genetics, such as polygenic testing.  The Human Genome Project, for example, has stimulated enormous interest in tracing types of behavior to particular strands of DNA located on specific chromosomes.

If these advances are not to be abused, then there will need to be a more general understanding of the fact that biology interacts with both the cultural context and the personal choices that people make about how they want to live their lives.

There is no neat and simple way of unraveling these qualitatively different and reciprocal influences on human behavior.

Epigenetics: Licking Rat Pups

Michael Meaney and his colleagues at McGill University in Montreal, Canada conducted the landmark epigenetic study on mother rats licking and grooming their pups.

This research found that the amount of licking and grooming received by rat pups during their early life could alter their epigenetic marks and influence their stress responses in adulthood.

Pups that received high levels of maternal care (i.e., more licking and grooming) had a reduced stress response compared to those that received low levels of maternal care.

Meaney’s work with rat maternal behavior and its epigenetic effects has provided significant insights into the understanding of early-life experiences, gene expression, and adult behavior.

It underscores the importance of the early-life environment and its long-term impacts on an individual’s mental health and stress resilience.

Epigenetics: The Agouti Mouse Study

Waterland and Jirtle’s 2003 study on the Agouti mouse is another foundational work in the field of epigenetics that demonstrated how nutritional factors during early development can result in epigenetic changes that have long-lasting effects on phenotype.

In this study, they focused on a specific gene in mice called the Agouti viable yellow (A^vy) gene. Mice with this gene can express a range of coat colors, from yellow to mottled to brown.

This variation in coat color is related to the methylation status of the A^vy gene: higher methylation is associated with the brown coat, and lower methylation with the yellow coat.

Importantly, the coat color is also associated with health outcomes, with yellow mice being more prone to obesity, diabetes, and tumorigenesis compared to brown mice.

Waterland and Jirtle set out to investigate whether maternal diet, specifically supplementation with methyl donors like folic acid, choline, betaine, and vitamin B12, during pregnancy could influence the methylation status of the A^vy gene in offspring.

Key findings from the study include:

Dietary Influence : When pregnant mice were fed a diet supplemented with methyl donors, their offspring had an increased likelihood of having the brown coat color. This indicated that the supplemented diet led to an increased methylation of the A^vy gene.

Health Outcomes : Along with the coat color change, these mice also had reduced risks of obesity and other health issues associated with the yellow phenotype.

Transgenerational Effects : The study showed that nutritional interventions could have effects that extend beyond the individual, affecting the phenotype of the offspring.

The implications of this research are profound. It highlights how maternal nutrition during critical developmental periods can have lasting effects on offspring through epigenetic modifications, potentially affecting health outcomes much later in life.

The study also offers insights into how dietary and environmental factors might contribute to disease susceptibility in humans.

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Further Information

• Genetic & Environmental Influences on Human Psychological Differences

Evidence for Nurture

• Classical Conditioning
• Little Albert Experiment
• Operant Conditioning
• Behaviorism
• Social Learning Theory
• Bronfenbrenner’s Ecological Systems Theory
• Social Roles
• Attachment Styles
• The Hidden Links Between Mental Disorders
• Visual Cliff Experiment
• Behavioral Genetics, Genetics, and Epigenetics
• Epigenetics
• Is Epigenetics Inherited?
• Physiological Psychology
• Bowlby’s Maternal Deprivation Hypothesis
• So is it nature not nurture after all?

Evidence for an Interaction

• Genes, Interactions, and the Development of Behavior
• Agouti Mouse Study
• Biological Psychology

What does nature refer to in the nature vs. nurture debate?

In the nature vs. nurture debate, “nature” refers to the influence of genetics, innate qualities, and biological factors on human development, behavior, and traits. It emphasizes the role of hereditary factors in shaping who we are.

What does nurture refer to in the nature vs. nurture debate?

In the nature vs. nurture debate, “nurture” refers to the influence of the environment, upbringing, experiences, and social factors on human development, behavior, and traits. It emphasizes the role of external factors in shaping who we are.

Why is it important to determine the contribution of heredity (nature) and environment (nurture) in human development?

Determining the contribution of heredity and environment in human development is crucial for understanding the complex interplay between genetic factors and environmental influences. It helps identify the relative significance of each factor, informing interventions, policies, and strategies to optimize human potential and address developmental challenges.

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Vygotsky vs. Piaget: A Paradigm Shift

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What Are Nature vs. Nurture Examples?

How is nature defined, how is nurture defined, the nature vs. nurture debate, nature vs. nurture examples, what is empiricism (extreme nurture position), contemporary views of nature vs. nurture.

Nature vs. nurture is an age-old debate about whether genetics (nature) plays a bigger role in determining a person's characteristics than lived experience and environmental factors (nurture). The term "nature vs. nature" was coined by English naturalist Charles Darwin's younger half-cousin, anthropologist Francis Galton, around 1875.

In psychology, the extreme nature position (nativism) proposes that intelligence and personality traits are inherited and determined only by genetics.

On the opposite end of the spectrum, the extreme nurture position (empiricism) asserts that the mind is a blank slate at birth; external factors like education and upbringing determine who someone becomes in adulthood and how their mind works. Both of these extreme positions have shortcomings and are antiquated.

This article explores the difference between nature and nurture. It gives nature vs. nurture examples and explains why outdated views of nativism and empiricism don't jibe with contemporary views. 

Thanasis Zovoilis / Getty Images

In the context of nature vs. nurture, "nature" refers to genetics and heritable factors that are passed down to children from their biological parents.

Genes and hereditary factors determine many aspects of someone’s physical appearance and other individual characteristics, such as a genetically inherited predisposition for certain personality traits.

Scientists estimate that 20% to 60% percent of temperament is determined by genetics and that many (possibly thousands) of common gene variations combine to influence individual characteristics of temperament.

However, the impact of gene-environment (or nature-nurture) interactions on someone's traits is interwoven. Environmental factors also play a role in temperament by influencing gene activity. For example, in children raised in an adverse environment (such as child abuse or violence), genes that increase the risk of impulsive temperamental characteristics may be activated (turned on).

Trying to measure "nature vs. nurture" scientifically is challenging. It's impossible to know precisely where the influence of genes and environment begin or end.

How Are Inherited Traits Measured?

“Heritability”   describes the influence that genes have on human characteristics and traits. It's measured on a scale of 0.0 to 1.0. Very strong heritable traits like someone's eye color are ranked a 1.0.

Traits that have nothing to do with genetics, like speaking with a regional accent ranks a zero. Most human characteristics score between a 0.30 and 0.60 on the heritability scale, which reflects a blend of genetics (nature) and environmental (nurture) factors.

Thousands of years ago, ancient Greek philosophers like Plato believed that "innate knowledge" is present in our minds at birth. Every parent knows that babies are born with innate characteristics. Anecdotally, it may seem like a kid's "Big 5" personality traits (agreeableness, conscientiousness, extraversion, neuroticism, and openness) were predetermined before birth.

What is the "Big 5" personality traits

The Big 5 personality traits is a theory that describes the five basic dimensions of personality. It was developed in 1949 by D. W. Fiske and later expanded upon by other researchers and is used as a framework to study people's behavior.

From a "nature" perspective, the fact that every child has innate traits at birth supports Plato's philosophical ideas about innatism. However, personality isn't set in stone. Environmental "nurture" factors can change someone's predominant personality traits over time. For example, exposure to the chemical lead during childhood may alter personality.

In 2014, a meta-analysis of genetic and environmental influences on personality development across the human lifespan found that people change with age. Personality traits are relatively stable during early childhood but often change dramatically during adolescence and young adulthood.

It's impossible to know exactly how much "nurture" changes personality as people get older. In 2019, a study of how stable personality traits are from age 16 to 66 found that people's Big 5 traits are both stable and malleable (able to be molded). During the 50-year span from high school to retirement, some traits like agreeableness and conscientiousness tend to increase, while others appear to be set in stone.

Nurture refers to all of the external or environmental factors that affect human development such as how someone is raised, socioeconomic status, early childhood experiences, education, and daily habits.

Although the word "nurture" may conjure up images of babies and young children being cared for by loving parents, environmental factors and life experiences have an impact on our psychological and physical well-being across the human life span. In adulthood, "nurturing" oneself by making healthy lifestyle choices can offset certain genetic predispositions.

For example, a May 2022 study found that people with a high genetic risk of developing the brain disorder Alzheimer's disease can lower their odds of developing dementia (a group of symptoms that affect memory, thinking, and social abilities enough to affect daily life) by adopting these seven healthy habits in midlife:

• Staying active
• Healthy eating
• Losing weight
• Not smoking
• Reducing blood sugar
• Controlling cholesterol
• Maintaining healthy blood pressure

The nature vs. nurture debate centers around whether individual differences in behavioral traits and personality are caused primarily by nature or nurture. Early philosophers believed the genetic traits passed from parents to their children influence individual differences and traits. Other well-known philosophers believed the mind begins as a blank slate and that everything we are is determined by our experiences.

While early theories favored one factor over the other, experts today recognize there is a complex interaction between genetics and the environment and that both nature and nurture play a critical role in shaping who we are.

Eye color and skin pigmentation are examples of "nature" because they are present at birth and determined by inherited genes. Developmental delays due to toxins (such as exposure to lead as a child or exposure to drugs in utero) are examples of "nurture" because the environment can negatively impact learning and intelligence.

In Child Development

The nature vs. nurture debate in child development is apparent when studying language development. Nature theorists believe genetics plays a significant role in language development and that children are born with an instinctive ability that allows them to both learn and produce language.

Nurture theorists would argue that language develops by listening and imitating adults and other children.

In addition, nurture theorists believe people learn by observing the behavior of others. For example, contemporary psychologist Albert Bandura's social learning theory suggests that aggression is learned through observation and imitation.

In Psychology

In psychology, the nature vs. nurture beliefs vary depending on the branch of psychology.

• Biopsychology:  Researchers analyze how the brain, neurotransmitters, and other aspects of our biology influence our behaviors, thoughts, and feelings. emphasizing the role of nature.
• Social psychology: Researchers study how external factors such as peer pressure and social media influence behaviors, emphasizing the importance of nurture.
• Behaviorism: This theory of learning is based on the idea that our actions are shaped by our interactions with our environment.

In Personality Development

Whether nature or nurture plays a bigger role in personality development depends on different personality development theories.

• Behavioral theories: Our personality is a result of the interactions we have with our environment, such as parenting styles, cultural influences, and life experiences.
• Biological theories: Personality is mostly inherited which is demonstrated by a study in the 1990s that concluded identical twins reared apart tend to have more similar personalities than fraternal twins.
• Psychodynamic theories: Personality development involves both genetic predispositions and environmental factors and their interaction is complex.

In Mental Illness

Both nature and nurture can contribute to mental illness development.

For example, at least five mental health disorders are associated with some type of genetic component ( autism ,  attention-deficit hyperactivity disorder (ADHD) ,  bipolar disorder , major depression, and  schizophrenia ).

Other explanations for mental illness are environmental, such as:

• Being exposed to drugs or alcohol in utero 
• Witnessing a traumatic event, leading to post-traumatic stress disorder (PTSD)
• Adverse life events and chronic stress during childhood

In Mental Health Therapy

Mental health treatment can involve both nature and nurture. For example, a therapist may explore life experiences that may have contributed to mental illness development (nurture) as well as family history of mental illness (nature).

At the same time, research indicates that a person's genetic makeup may impact how their body responds to antidepressants. Taking this into consideration is important for finding the right treatment for each individual.

 What Is Nativism (Extreme Nature Position)?

Innatism emphasizes nature's role in shaping our minds and personality traits before birth. Nativism takes this one step further and proposes that all of people's mental and physical characteristics are inherited and predetermined at birth.

In its extreme form, concepts of nativism gave way to the early 20th century's racially-biased eugenics movement. Thankfully, "selective breeding," which is the idea that only certain people should reproduce in order to create chosen characteristics in offspring, and eugenics, arranged breeding, lost momentum during World War II. At that time, the Nazis' ethnic cleansing (killing people based on their ethnic or religious associations) atrocities were exposed.

Philosopher John Locke's tabula rasa theory from 1689 directly opposes the idea that we are born with innate knowledge. "Tabula rasa" means "blank slate" and implies that our minds do not have innate knowledge at birth.

Locke was an empiricist who believed that all the knowledge we gain in life comes from sensory experiences (using their senses to understand the world), education, and day-to-day encounters after being born.

Today, looking at nature vs. nature in black-and-white terms is considered a misguided dichotomy (two-part system). There are so many shades of gray where nature and nurture overlap. It's impossible to tease out how inherited traits and learned behaviors shape someone's unique characteristics or influence how their mind works.

The influences of nature and nurture in psychology are impossible to unravel. For example, imagine someone growing up in a household with an alcoholic parent who has frequent rage attacks. If that child goes on to develop a substance use disorder and has trouble with emotion regulation in adulthood, it's impossible to know precisely how much genetics (nature) or adverse childhood experiences (nurture) affected that individual's personality traits or issues with alcoholism.

Epigenetics Blurs the Line Between Nature and Nurture

"Epigenetics " means "on top of" genetics. It refers to external factors and experiences that turn genes "on" or "off." Epigenetic mechanisms alter DNA's physical structure in utero (in the womb) and across the human lifespan.

Epigenetics blurs the line between nature and nurture because it says that even after birth, our genetic material isn't set in stone; environmental factors can modify genes during one's lifetime. For example, cannabis exposure during critical windows of development can increase someone's risk of neuropsychiatric disease via epigenetic mechanisms.

Nature vs. nurture is a framework used to examine how genetics (nature) and environmental factors (nurture) influence human development and personality traits.

However, nature vs. nurture isn't a black-and-white issue; there are many shades of gray where the influence of nature and nurture overlap. It's impossible to disentangle how nature and nurture overlap; they are inextricably intertwined. In most cases, nature and nurture combine to make us who we are. 

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Damian RI, Spengler M, Sutu A, Roberts BW. Sixteen going on sixty-six: A longitudinal study of personality stability and change across 50 years .  Journal of Personality and Social Psychology . 2019;117(3):674-695. doi:10.1037/pspp0000210

Tin A, Bressler J, Simino J, et al. Genetic risk, midlife life’s simple 7, and incident dementia in the atherosclerosis risk in communities study .  Neurology . Published online May 25, 2022. doi:10.1212/WNL.0000000000200520 

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The Nature vs. Nurture Debate

Genetic and Environmental Influences and How They Interact

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Verywell / Joshua Seong

• Definitions
• Interaction
• Contemporary Views

Nature refers to how genetics influence an individual's personality, whereas nurture refers to how their environment (including relationships and experiences) impacts their development. Whether nature or nurture plays a bigger role in personality and development is one of the oldest philosophical debates within the field of psychology .

Learn how each is defined, along with why the issue of nature vs. nurture continues to arise. We also share a few examples of when arguments on this topic typically occur, how the two factors interact with each other, and contemporary views that exist in the debate of nature vs. nurture as it stands today.

Nature and Nurture Defined

To better understand the nature vs. nurture argument, it helps to know what each of these terms means.

• Nature refers largely to our genetics . It includes the genes we are born with and other hereditary factors that can impact how our personality is formed and influence the way that we develop from childhood through adulthood.
• Nurture encompasses the environmental factors that impact who we are. This includes our early childhood experiences, the way we were raised , our social relationships, and the surrounding culture.

A few biologically determined characteristics include genetic diseases, eye color, hair color, and skin color. Other characteristics are tied to environmental influences, such as how a person behaves, which can be influenced by parenting styles and learned experiences.

For example, one child might learn through observation and reinforcement to say please and thank you. Another child might learn to behave aggressively by observing older children engage in violent behavior on the playground.

The Debate of Nature vs. Nurture

The nature vs. nurture debate centers on the contributions of genetics and environmental factors to human development. Some philosophers, such as Plato and Descartes, suggested that certain factors are inborn or occur naturally regardless of environmental influences.

Advocates of this point of view believe that all of our characteristics and behaviors are the result of evolution. They contend that genetic traits are handed down from parents to their children and influence the individual differences that make each person unique.

Other well-known thinkers, such as John Locke, believed in what is known as tabula rasa which suggests that the mind begins as a blank slate . According to this notion, everything that we are is determined by our experiences.

Behaviorism is a good example of a theory rooted in this belief as behaviorists feel that all actions and behaviors are the results of conditioning. Theorists such as John B. Watson believed that people could be trained to do and become anything, regardless of their genetic background.

People with extreme views are called nativists and empiricists. Nativists take the position that all or most behaviors and characteristics are the result of inheritance. Empiricists take the position that all or most behaviors and characteristics result from learning.

Examples of Nature vs. Nurture

One example of when the argument of nature vs. nurture arises is when a person achieves a high level of academic success . Did they do so because they are genetically predisposed to elevated levels of intelligence, or is their success a result of an enriched environment?

The argument of nature vs. nurture can also be made when it comes to why a person behaves in a certain way. If a man abuses his wife and kids, for instance, is it because he was born with violent tendencies, or is violence something he learned by observing others in his life when growing up?

Nature vs. Nurture in Psychology

Throughout the history of psychology , the debate of nature vs. nurture has continued to stir up controversy. Eugenics, for example, was a movement heavily influenced by the nativist approach.

Psychologist Francis Galton coined the terms 'nature versus nurture' and 'eugenics' and believed that intelligence resulted from genetics. Galton also felt that intelligent individuals should be encouraged to marry and have many children, while less intelligent individuals should be discouraged from reproducing.

The value placed on nature vs. nurture can even vary between the different branches of psychology , with some branches taking a more one-sided approach. In biopsychology , for example, researchers conduct studies exploring how neurotransmitters influence behavior, emphasizing the role of nature.

In social psychology , on the other hand, researchers might conduct studies looking at how external factors such as peer pressure and social media influence behaviors, stressing the importance of nurture. Behaviorism is another branch that focuses on the impact of the environment on behavior.

Nature vs. Nurture in Child Development

Some psychological theories of child development place more emphasis on nature and others focus more on nurture. An example of a nativist theory involving child development is Chomsky's concept of a language acquisition device (LAD). According to this theory, all children are born with an instinctive mental capacity that allows them to both learn and produce language.

An example of an empiricist child development theory is Albert Bandura's social learning theory . This theory says that people learn by observing the behavior of others. In his famous Bobo doll experiment , Bandura demonstrated that children could learn aggressive behaviors simply by observing another person acting aggressively.

Nature vs. Nurture in Personality Development

There is also some argument as to whether nature or nurture plays a bigger role in the development of one's personality. The answer to this question varies depending on which personality development theory you use.

According to behavioral theories, our personality is a result of the interactions we have with our environment, while biological theories suggest that personality is largely inherited. Then there are psychodynamic theories of personality that emphasize the impact of both.

Nature vs. Nurture in Mental Illness Development

One could argue that either nature or nurture contributes to mental health development. Some causes of mental illness fall on the nature side of the debate, including changes to or imbalances with chemicals in the brain. Genetics can also contribute to mental illness development, increasing one's risk of a certain disorder or disease.

Mental disorders with some type of genetic component include autism , attention-deficit hyperactivity disorder (ADHD), bipolar disorder , major depression , and schizophrenia .

Other explanations for mental illness are environmental. This includes being exposed to environmental toxins, such as drugs or alcohol, while still in utero. Certain life experiences can also influence mental illness development, such as witnessing a traumatic event, leading to the development of post-traumatic stress disorder (PTSD).

Nature vs. Nurture in Mental Health Therapy

Different types of mental health treatment can also rely more heavily on either nature or nurture in their treatment approach. One of the goals of many types of therapy is to uncover any life experiences that may have contributed to mental illness development (nurture).

However, genetics (nature) can play a role in treatment as well. For instance, research indicates that a person's genetic makeup can impact how their body responds to antidepressants. Taking this into consideration is important for getting that person the help they need.

Interaction Between Nature and Nurture

Which is stronger: nature or nurture? Many researchers consider the interaction between heredity and environment—nature with nurture as opposed to nature versus nurture—to be the most important influencing factor of all.

For example, perfect pitch is the ability to detect the pitch of a musical tone without any reference. Researchers have found that this ability tends to run in families and might be tied to a single gene. However, they've also discovered that possessing the gene is not enough as musical training during early childhood is needed for this inherited ability to manifest itself.

Height is another example of a trait influenced by an interaction between nature and nurture. A child might inherit the genes for height. However, if they grow up in a deprived environment where proper nourishment isn't received, they might never attain the height they could have had if they'd grown up in a healthier environment.

A newer field of study that aims to learn more about the interaction between genes and environment is epigenetics . Epigenetics seeks to explain how environment can impact the way in which genes are expressed.

Some characteristics are biologically determined, such as eye color, hair color, and skin color. Other things, like life expectancy and height, have a strong biological component but are also influenced by environmental factors and lifestyle.

Contemporary Views of Nature vs. Nurture

Most experts recognize that neither nature nor nurture is stronger than the other. Instead, both factors play a critical role in who we are and who we become. Not only that but nature and nurture interact with each other in important ways all throughout our lifespan.

As a result, many in this field are interested in seeing how genes modulate environmental influences and vice versa. At the same time, this debate of nature vs. nurture still rages on in some areas, such as in the origins of homosexuality and influences on intelligence .

While a few people take the extreme nativist or radical empiricist approach, the reality is that there is not a simple way to disentangle the multitude of forces that exist in personality and human development. Instead, these influences include genetic factors, environmental factors, and how each intermingles with the other.

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National Institutes of Health. Common genetic factors found in 5 mental disorders .

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Levitt M. Perceptions of nature, nurture and behaviour . Life Sci Soc Policy . 2013;9:13. doi:10.1186/2195-7819-9-13

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By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Nature vs. Nurture

Reviewed by Psychology Today Staff

The expression “nature vs. nurture” describes the question of how much a person's characteristics are formed by either “nature” or “nurture.” “Nature” means innate biological factors (namely genetics ), while “nurture” can refer to upbringing or life experience more generally.

Traditionally, “nature vs. nurture” has been framed as a debate between those who argue for the dominance of one source of influence or the other, but contemporary experts acknowledge that both “nature” and “nurture” play a role in psychological development and interact in complex ways.

• The Meaning of Nature vs. Nurture
• The Nature-vs.-Nurture Debate
• Identifying Genetic and Environmental Factors

The wording of the phrase “nature vs. nurture” makes it seem as though human individuality— personality traits, intelligence , preferences, and other characteristics—must be based on either the genes people are born with or the environment in which they grew up. The reality, as scientists have shown, is more complicated, and both these and other factors can help account for the many ways in which individuals differ from each other.

The words “nature” and “nurture” themselves can be misleading. Today, “ genetics ” and “environment” are frequently used in their place—with one’s environment including a broader range of experiences than just the nurturing received from parents or caregivers. Further, nature and nurture (or genetics and environment) do not simply compete to influence a person, but often interact with each other; “nature and nurture” work together. Finally, individual differences do not entirely come down to a person’s genetic code or developmental environment—to some extent, they emerge due to messiness in the process of development as well.

A person’s biological nature can affect a person’s experience of the environment. For example, a person with a genetic disposition toward a particular trait, such as aggressiveness, may be more likely to have particular life experiences (including, perhaps, receiving negative reactions from parents or others). Or, a person who grows up with an inclination toward warmth and sociability may seek out and elicit more positive social responses from peers. These life experiences could, in turn, reinforce an individual’s initial tendencies. Nurture or life experience more generally may also modify the effects of nature—for example, by expanding or limiting the extent to which a naturally bright child receives encouragement, access to quality education , and opportunities for achievement.

Epigenetics—the science of modifications in how genes are expressed— illustrates the complex interplay between “nature” and “nurture.” An individual’s environment, including factors such as early-life adversity, may result in changes in the way that parts of a person’s genetic code are “read.” While these epigenetic changes do not override the important influence of genes in general, they do constitute additional ways in which that influence is filtered through “nurture” or the environment.

Theorists and researchers have long battled over whether individual traits and abilities are inborn or are instead forged by experiences after birth. The debate has had broad implications: The real or perceived sources of a person’s strengths and vulnerabilities matter for fields such as education, philosophy , psychiatry , and clinical psychology. Today’s consensus—that individual differences result from a combination of inherited and non-genetic factors—strikes a more nuanced middle path between nature- or nurture-focused extremes.

The debate about nature and nurture has roots that stretch back at least thousands of years, to Ancient Greek theorizing about the causes of personality. During the modern era, theories emphasizing the role of either learning and experience or biological nature have risen and fallen in prominence—with genetics gaining increasing acknowledgment as an important (though not exclusive) influence on individual differences in the later 20th century and beyond.

“Nature versus nurture” was used by English scientist Francis Galton. In 1874, he published the book English Men of Science: Their Nature and Nurture , arguing that inherited factors were responsible for intelligence and other characteristics.

Genetic determinism emphasizes the importance of an individual’s nature in development. It is the view that genetics is largely or totally responsible for an individual’s psychological characteristics and behavior. The term “biological determinism” is often used synonymously.

The blank slate (or “tabula rasa”) view of the mind emphasizes the importance of nurture and the environment. Notably described by English philosopher John Locke in the 1600s, it proposed that individuals are born with a mind like an unmarked chalkboard and that its contents are based on experience and learning. In the 20th century, major branches of psychology proposed a primary role for nurture and experience , rather than nature, in development, including Freudian psychoanalysis and behaviorism.

Modern scientific methods have allowed researchers to advance further in understanding the complex relationships between genetics, life experience, and psychological characteristics, including mental health conditions and personality traits. Overall, the findings of contemporary studies underscore that with some exceptions—such as rare diseases caused by mutations in a single gene—no one factor, genetic or environmental, solely determines how a characteristic develops.

Scientists use multiple approaches to estimate how important genetics are for any given trait, but one of the most influential is the twin study. While identical (or monozygotic) twins share the same genetic code, fraternal (or dizygotic) twins share about 50 percent of the same genes, like typical siblings. Scientists are able to estimate the degree to which the variation in a particular trait, like extraversion , is explained by genetics in part by analyzing how similar identical twins are on that trait, compared to fraternal twins. ( These studies do have limitations, and estimates based on one population may not closely reflect all other populations.) 

It’s hard to call either “nature” or “nurture,” genes or the environment, more important to human psychology. The impact of one set of factors or the other depends on the characteristic, with some being more strongly related to one’s genes —for instance, autism appears to be more heritable than depression . But in general, psychological traits are shaped by a balance of interacting genetic and non-genetic influences.

Both genes and environmental factors can contribute to a person developing mental illness. Research finds that a major part of the variation in the risk for psychiatric conditions such as autism spectrum disorder, anxiety disorders, depression, and schizophrenia can be attributed to genetic differences. But not all of that risk is genetic, and life experiences, such as early-life abuse or neglect, may also affect risk of mental illness (and some individuals, based on their genetics, are likely more susceptible to environmental effects than others).

Like other psychological characteristics, personality is partly heritable. Research suggests less than half of the difference between people on measures of personality traits can be attributed to genes (one recent overall estimate is 40 percent). Non-genetic factors appear to be responsible for an equal or greater portion of personality differences between individuals. Some theorize that the social roles people adopt and invest in as they mature are among the more important non-genetic factors in personality development.

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Article contents

Nature and nurture as an enduring tension in the history of psychology.

• Hunter Honeycutt Hunter Honeycutt Bridgewater College, Department of Psychology
• https://doi.org/10.1093/acrefore/9780190236557.013.518
• Published online: 30 September 2019

Nature–nurture is a dichotomous way of thinking about the origins of human (and animal) behavior and development, where “nature” refers to native, inborn, causal factors that function independently of, or prior to, the experiences (“nurture”) of the organism. In psychology during the 19th century, nature-nurture debates were voiced in the language of instinct versus learning. In the first decades of the 20th century, it was widely assumed that that humans and animals entered the world with a fixed set of inborn instincts. But in the 1920s and again in the 1950s, the validity of instinct as a scientific construct was challenged on conceptual and empirical grounds. As a result, most psychologists abandoned using the term instinct but they did not abandon the validity of distinguishing between nature versus nurture. In place of instinct, many psychologists made a semantic shift to using terms like innate knowledge, biological maturation, and/or hereditary/genetic effects on development, all of which extend well into the 21st century. Still, for some psychologists, the earlier critiques of the instinct concept remain just as relevant to these more modern usages.

The tension in nature-nurture debates is commonly eased by claiming that explanations of behavior must involve reference to both nature-based and nurture-based causes. However, for some psychologists there is a growing pressure to see the nature–nurture dichotomy as oversimplifying the development of behavior patterns. The division is seen as both arbitrary and counterproductive. Rather than treat nature and nurture as separable causal factors operating on development, they treat nature-nurture as a distinction between product (nature) versus process (nurture). Thus there has been a longstanding tension about how to define, separate, and balance the effects of nature and nurture.

• nature–nurture
• development
• nativism–empiricism
• innate–learned
• behavioral genetics
• epigenetics

Nature and Nurture in Development

The oldest and most persistent ways to frame explanations about the behavioral and mental development of individuals is to distinguish between two separate sources of developmental causation: (a) intrinsic, preformed, or predetermined causes (“nature”) versus (b) extrinsic, experiential, or environmental causes (“nurture”). Inputs from these two sources are thought to add their own contribution to development (see Figure 1 ).

Figure 1. The traditional view of nature and nurture as separate causes of development. In the traditional view, nature and nurture are treated as independent causal influences that combine during development to generate outcomes. Note that, during development, the effects of nature and nurture (shown in horizontal crossing lines) remain independent so that their effects on outcomes are theoretically separable.

Because some traits seem to derive more from one source than the other, much of the tension associated with the nature–nurture division deals with disagreements about how to balance the roles of nature and nurture in the development of a trait.

Evidence of Nature in Development

Evidence to support the nature–nurture division usually derives from patterns of behavior that suggest a limited role of environmental causation, thus implying some effect of nature by default. Table 1 depicts some common descriptors and conditions used to infer that some preference, knowledge, or skill is nature based.

Table 1. Common Descriptors and Associated Conditions for Inferring the Effects of Nature on Development

It is important to reiterate that nature-based causation (e.g., genetic determination) is inferred from these observations. Such inferences can generate tension because each of the observations listed here can be explained by nurture-based (environmental) factors. Confusion can also arise when evidence of one descriptor (e.g., being hereditary) is erroneously used to justify a different usage (e.g., that the trait is unlearned).

The Origins of Nature Versus Nurture

For much of recorded history, the distinction between nature and nurture was a temporal divide between what a person is innately endowed with at birth, prior to experience (nature), and what happens thereafter (nurture). It was not until the 19th century that the temporal division was transformed into a material division of causal influences (Keller, 2010 ). New views about heredity and Darwinian evolution justified distinguishing between native traits and genetic causes from acquired traits and environmental causes. More so than before, the terms nature and nurture were often juxtaposed in an opposition famously described by Sir Francis Galton ( 1869 ) as that between “nature versus nurture.”

Galton began writing about heredity in the mid-1860s. He believed we would discover laws governing the transmission of mental as well as physical qualities. Galton’s take on mental heredity, however, was forged by his desire to improve the human race in a science he would later call “eugenics.” In the mid- 19th century , British liberals assumed humans were equivalent at birth. Their social reform efforts were geared to enhancing educational opportunities and improving living conditions. Galton, a political conservative, opposed the notion of natural equality, arguing instead that people were inherently different at birth (Cowan, 2016 ), and that these inherited mental and behavioral inequalities were transmitted through lineages like physical qualities. Because Galton opposed the widely held Lamarckian idea that the qualities acquired in one’s lifetime could modify the inherited potential of subsequent generations, he believed long-lasting improvement of the human stock would only come by controlling breeding practices.

To explain the biological mechanisms of inheritance, Galton joined a growing trend in the 1870s to understand inheritance as involving the transmission of (hypothetical) determinative, germinal substances across generations. Foreshadowing a view that would later become scientific orthodoxy, Galton believed these germinal substances to be uninfluenced by the experiences of the organism. His theory of inheritance, however, was speculative. Realizing he was not equipped to fully explicate his theory of biological inheritance, Galton abandoned this line of inquiry by the end of that decade and refocused his efforts on identifying statistical laws of heredity of individual differences (Renwick, 2011 ).

Historians generally agree that Galton was the first to treat nature (as heredity) and nurture (everything else) as separate causal forces (Keller, 2010 ), but the schism gained biological legitimacy through the work of the German cytologist Auguste Weismann in the 1880s. Whereas Galton’s theory was motivated by his political agenda, Weismann was motivated by a scientific, theoretical agenda. Namely, Weismann opposed Lamarckian inheritance and promoted a view of evolution driven almost entirely by natural selection.

Drawing upon contemporary cytological and embryological research, Weismann made the case that the determinative substances found in the germ cells of plants and animals (called the “germ-plasm”) that are transmitted across generations were physically sequestered very early in embryogenesis and remained buffered from the other cells of the body (“somato-plasm”). This so-called, Weismann’s barrier meant that alterations in the soma that develop in the lifetime of the organism through the use or disuse of body parts would not affect the germinal substances transmitted during reproduction (see Winther, 2001 , for review). On this view, Lamarckian-style inheritance of acquired characteristics was not biologically possible.

Galton and Weismann’s influence on the life sciences cannot be overstated. Their work convinced many to draw unusually sharp distinctions between the inherited (nature) and the acquired (nurture). Although their theories were met with much resistance and generated significant tension in the life sciences from cytology to psychology, their efforts helped stage a new epistemic space through which to appreciate Mendel’s soon to be rediscovered breeding studies and usher in genetics (Muller-Wille & Rheinberger, 2012 ).

Ever since, psychology has teetered between nature-biased and nurture-biased positions. With the rise of genetics, the wedge between nature–nurture was deepened in the early to mid- 20th century , creating fields of study that focused exclusively on the effects of either nature or nurture.

The “Middle Ground” Perspective on Nature–Nurture

Twenty-first-century psychology textbooks often state that the nature–nurture debates have been resolved, and the tension relaxed, because we have moved on from emphasizing nature or nurture to appreciating that development necessarily involves both nature and nurture. In this middle-ground position, one asks how nature and nurture interact. For example, how do biological (or genetic) predispositions for behaviors or innate knowledge bias early learning experiences? Or how might environmental factors influence the biologically determined (maturational) unfolding of bodily form and behaviors?

Rejection of the Nature–Nurture Divide

For some, the “middle-ground” resolution is as problematic as “either/or” views and does not resolve a deeper source of tension inherent in the dichotomy. On this view, the nature–nurture divide is neither a legitimate nor a constructive way of thinking about development. Instead, developmental analysis reveals that the terms commonly associated with nature (e.g., innate, genetic, hereditary, or instinctual) and nurture (environmental or learned) are so entwined and confounded (and often arbitrary) that their independent effects cannot be meaningfully discussed. The nature–nurture division oversimplifies developmental processes, takes too much for granted, and ultimately hinders scientific progress. Thus not only is there a lingering tension about how to balance the effects of nature and nurture in the middle-ground view, but there is also a growing tension to move beyond the dichotomous nature–nurture framework.

Nativism in Behavior: Instincts

Definitions of instinct can vary tremendously, but many contrast (a) instinct with reason (or intellect, thought, will), which is related to but separable from contrasting (b) instinct with learning (or experience or habit).

Instinct in the Age of Enlightenment

Early usages of the instinct concept, following Aristotle, treated instinct as a mental, estimative faculty ( vis aestimativa or aestimativa naturalis ) in humans and animals that allowed for the judgments of objects in the world (e.g., seeing a predator) to be deemed beneficial or harmful in a way that transcends immediate sensory experience but does not involve the use of reason (Diamond, 1971 ). In many of the early usages, the “natural instinct” of animals even included subrational forms of learning.

The modern usage of instincts as unlearned behaviors took shape in the 17th century . By that point it was widely believed that nature or God had implanted in animals and humans innate behaviors and predispositions (“instincts”) to promote the survival of the individual and the propagation of the species. Disagreements arose as to whether instincts derived from innate mental images or were mindlessly and mechanically (physiologically) generated from innately specified bodily organization (Richards, 1987 ).

Anti-Instinct Movement in the Age of Enlightenment

Challenges to the instinct concept can be found in the 16th century (see Diamond, 1971 ), but they were most fully developed by empiricist philosophers of the French Sensationalist tradition in the 18th century (Richards, 1987 ). Sensationalists asserted that animals behaved rationally and all of the so-called instincts displayed by animals could be seen as intelligently acquired habits.

For Sensationalists, instincts, as traditionally understood, did not exist. Species-specificity in behavior patterns could be explained by commonalities in physiological organization, needs, and environmental conditions. Even those instinctual behaviors seen at birth (e.g., that newly hatched chicks peck and eat grain) might eventually be explained by the animal’s prenatal experiences. Erasmus Darwin ( 1731–1802 ), for example, speculated that the movements and swallowing experiences in ovo could account for the pecking and eating of grain by young chicks. The anti-instinct sentiment was clearly expressed by the Sensationalist Jean Antoine Guer ( 1713–1764 ), who warned that instinct was an “infantile idea” that could only be held by those who are ignorant of philosophy, that traditional appeals to instincts in animals not only explained nothing but served to hinder scientific explanations, and that nothing could be more superficial than to explain behavior than appealing to so-called instincts (Richards, 1987 ).

The traditional instinct concept survived. For most people, the complex, adaptive, species-specific behaviors displayed by naïve animals (e.g., caterpillars building cocoons; infant suckling behaviors) appeared to be predetermined and unlearned. Arguably as important, however, was the resistance to the theological implications of Sensationalist philosophy.

One of the strongest reactions to Sensationalism was put forward in Germany by Herman Samuel Reimarus ( 1694–1768 ). As a natural theologian, Reimarus, sought evidence of a God in the natural world, and the species-specific, complex, and adaptive instincts of animals seemed to stand as the best evidence of God’s work. More so than any other, Reimarus extensively catalogued instincts in humans and animals. Rather than treat instincts as behaviors, he defined instincts as natural impulses (inner drives) to act that were expressed perfectly, without reflection or practice, and served adaptive goals (Richards, 1987 ). He even proposed instincts for learning, a proposal that would resurface in the mid- 20th century , as would his drive theory of instinct (Jaynes & Woodward, 1974 ).

Partly as a result of Reimarus’ efforts, the instinct concept survived going into the 19th century . But many issues surrounding the instinct concept were left unsettled. How do instincts differ from reflexive behaviors? What role does learning play in the expression of instincts, if any? Do humans have more or fewer instincts than animals? These questions would persist well into the first decades of the 20th century and ultimately fuel another anti-instinct movement.

Instinct in the 19th Century

In the 19th century , the tension about the nature and nurture of instincts in the lifetime of animals led to debates about the nature and nurture of instincts across generations . These debates dealt with whether instincts should be viewed as “inherited habits” from previous generations or whether they result from the natural selection. Debating the relative roles of neo-Lamarckian use-inheritance versus neo-Darwinian natural selection in the transmutation of species became a significant source of tension in the latter half of the 19th century . Although the neo-Lamarckian notion of instincts as being inherited habits was rejected in the 20th century , it has resurged in recent years (e.g., see Robinson & Barron, 2017 ).

Darwinian evolutionary theory required drawing distinctions between native and acquired behaviors, and, perhaps more so than before, behaviors were categorized along a continuum from the purely instinctive (unlearned), to the partially instinctive (requiring some learning), to the purely learned. Still, it was widely assumed that a purely instinctive response would be modified by experience after its first occurrence. As a result, instinct and habit were very much entangled in the lifetime of the organism. The notion of instincts as fixed and unmodifiable would not be widely advanced until after the rise of Weismann’s germ-plasm theory in the late 19thcentury .

Given their importance in evolutionary theory, there was greater interest in more objectively identifying pure instincts beyond anecdotal reports. Some of the most compelling evidence was reported by Douglas Spalding ( 1844–1877 ) in the early 1870s (see Gray, 1967 ). Spalding documented numerous instances of how naïve animals showed coordinated, seemingly adaptive responses (e.g., hiding) to objects (e.g., sight of predators) upon their first encounter, and he helped pioneer the use of the deprivation experiment to identify instinctive behaviors. This technique involved selectively depriving young animals of seemingly critical learning experiences or sensory stimulation. Should animals display some species-typical action following deprivation, then, presumably, the behavior could be labeled as unlearned or innate. In all, these studies seemed to show that animals displayed numerous adaptive responses at the very start, prior to any relevant experience. In a variety of ways, Spalding’s work anticipated 20th-century studies of innate behavior. Not only would the deprivation experiment be used as the primary means of detecting native tendencies by European zoologists and ethologists, but Spalding also showed evidence of what would later be called imprinting, critical period effects and evidence of behavioral maturation.

Reports of pure instinct did not go unchallenged. Lloyd Morgan ( 1896 ) questioned the accuracy of these reports in his own experimental work with young animals. In some cases, he failed to replicate the results and in other cases he found that instinctive behaviors were not as finely tuned to objects in the environment as had been claimed. Morgan’s research pointed to taking greater precision in identifying learned and instinctive components of behavior, but, like most at the turn of the 20th century , he did not question that animal behavior involved both learned and instinctive elements.

A focus on instinctive behaviors intensified in the 1890s as Weismann’s germ-plasm theory grew in popularity. More so than before, a sharp distinction was drawn between native and acquired characteristics, including behavior (Johnston, 1995 ). Although some psychologists continued to maintain neo-Lamarckian notions, most German (Burnham, 1972 ) and American (Cravens & Burnham, 1971 ) psychologists were quick to adopt Weismann’s theory. They envisioned a new natural science of psychology that would experimentally identify the germinally determined, invariable set of native psychological traits in species and their underlying physiological (neural) basis. However, whereas English-speaking psychologists tended to focus on how this view impacted our understanding of social institutions and its social implications, German psychologists were more interested in the longstanding philosophical implications of Weismann’s doctrine as it related to the differences (if any) between man and beast (Burnham, 1972 ).

Some anthropologists and sociologists, however, interpreted Weismann’s theory quite differently and used it elevate sociology as its own scientific discipline. In the 1890s, the French sociologist Emil Durkheim, for example, interpreted Weismann’s germinal determinants as a generic force on human behavior that influenced the development of general predispositions that are molded by the circumstances of life (Meloni, 2016 ). American anthropologists reached similar conclusions in the early 20th century (Cravens & Burnham, 1971 ). Because Weismann’s theory divorced biological inheritance from social inheritance, and because heredity was treated as a generic force, sociologists felt free to study social (eventually, “cultural”) phenomena without reference to biological or psychological concerns.

Anti-Instinct Movement in the 1920s

Despite their differences, in the first two decades of the 20th century both psychologists and sociologists generally assumed that humans and animals had some native tendencies or instincts. Concerns were even voiced that instinct had not received enough attention in psychology. Disagreements about instincts continued to focus on (the now centuries old debates of) how to conceptualize them. Were they complex reflexes, impulses, or motives to act, or should instinct be a mental faculty (like intuition), separate from reasoning and reflex (Herrnstein, 1972 )?

In America, the instinct concept came under fire following a brief paper in 1919 by Knight Dunlap titled “Are There Any Instincts?” His primary concern dealt with teleological definitions of instincts in which an instinct referred to all the activities involved in obtaining some end-state (e.g., instincts of crying, playing, feeding, reproduction, war, curiosity, or pugnacity). Defined in this way, human instincts were simply labels for human activities, but how these activities were defined was arbitrarily imposed by the researchers. Is feeding, for instance, an instinct, or is it composed of more basic instincts (like chewing and swallowing)? The arbitrariness of classifying human behavior had led to tremendous inconsistencies and confusion among psychologists.

Not all of the challenges to instinct dealt with its teleological usage. Some of the strongest criticisms were voiced by Zing-Yang Kuo throughout the 1920s. Kuo was a Chinese animal psychologist who studied under Charles Tolman at the University of California, Berkeley. Although Kuo’s attacks on instinct changed throughout the 1920s (see Honeycutt, 2011 ), he ultimately argued that all behaviors develop in experience-dependent ways and that appeals to instinct were statements of ignorance about how behaviors develop. Like Dunlap, he warned that instincts were labels with no explanatory value. To illustrate, after returning to China, he showed how the so-called rodent-killing instinct in cats often cited by instinct theorists is not found in kittens that are reared with rodents (Kuo, 1930 ). These kittens, instead, became attached to the rodents, and they resisted attempts to train rodent-killing. Echoing the point made by Guer, Kuo claimed that appeals to instinct served to stunt scientific inquiry into the developmental origins of behavior.

But Kuo did not just challenge the instinct concept. He also argued against labeling behaviors as “learned.” After all, whether an animal “learns” depends on the surrounding environmental conditions, the physiological and developmental status of the animal, and, especially, the developmental (or experiential) history of that animal. Understanding learning also required developmental analysis. Thus Kuo targeted the basic distinction between nature and nurture, and he was not alone in doing so (e.g., see Carmichael, 1925 ), but his call to reject it did not spread to mainstream American psychologists.

By the 1930s, the term instinct had fallen into disrepute in psychology, but experimental psychologists (including behaviorists) remained committed to a separation of native from acquired traits. If anything, the dividing line between native and acquired behaviors became more sharply drawn than before (Logan & Johnston, 2007 ). For some psychologists, instinct was simply rebranded in the less contentious (but still problematic) language of biological drives or motives (Herrnstein, 1972 ). Many other psychologists simply turned to describing native traits as due to “maturation” and/or “heredity” rather than “instinct.”

Fixed Action Patterns

The hereditarian instinct concept received a reboot in Europe in the 1930s with the rise of ethology led by Konrad Lorenz, Niko Tinbergen, and others. Just as animals inherit organs that perform specific functions, ethologists believed animals inherit behaviors that evolved to serve adaptive functions as well. Instincts were described as unlearned (inherited), blind, stereotyped, adaptive, fixed action patterns, impervious to change that are initiated (released) by specific stimuli in the environment.

Ethologists in 1930s and 1940s were united under the banner of innateness. They were increasingly critical of the trend by American psychologists (i.e., behaviorists) to focus on studying on how a limited number of domesticated species (e.g., white rat) responded to training in artificial settings (Burkhardt, 2005 ). Ethologists instead began with rich descriptions of animal behavior in more natural environments along with detailed analyses of the stimulus conditions that released the fixed action patterns. To test whether behavioral components were innate, ethologists relied primarily on the deprivation experiment popularized by Spalding in the 19th century . Using these methods (and others), ethologists identified numerous fascinating examples of instinctive behaviors, which captured mainstream attention.

In the early 1950s, shortly after ethology had gained professional status (Burkhardt, 2005 ), a series of challenges regarding instinct and innateness were put forth by a small cadre of North American behavioral scientists (e.g., T. C. Schneirla, Donald Hebb, Frank Beach). Arguably the most influential critique was voiced by comparative psychologist Daniel Lehrman ( 1953 ), who presented a detailed and damning critique of deprivation experiments on empirical and logical grounds. Lehrman explained that deprivation experiments isolate the animal from some but not all experiences. Thus deprivation experiments simply change what an animal experiences rather than eliminating experience altogether, and so they cannot possibly determine whether a behavior is innate (independent of experience). Instead, these experiments show what environmental conditions do not matter in the development of a behavior but do not speak to what conditions do matter .

Lehrman went on to argue that the whole endeavor to identify instinctive or innate behavior was misguided from the start. All behavior, according to Lehrman, develops from a history of interactions between an organism and its environment. If a behavior is found to develop in the absence of certain experiences, the researcher should not stop and label it as innate. Rather, research should continue to identify the conditions under which the behavior comes about. In line with Kuo, Lehrman repeated the warning that to label something as instinctive (or inherited or maturational) is a statement of ignorance about how that behavior develops and does more to stunt than promote research.

Lehrman’s critique created significant turmoil among ethologists. As a result, ethologists took greater care in using the term innate , and it led to new attempts to synthesize or re-envision learning and instinct .

Some of these attempts focused on an increased role for learning and experience in the ontogeny of species-typical behaviors. These efforts spawned significant cross-talk between ethologists and comparative psychologists to more thoroughly investigate behavioral development under natural conditions. Traditional appeals to instinct and learning (as classical and operant conditioning) were both found to be inadequate for explaining animal behavior. In their stead, these researchers focused more closely on how anatomical, physiological, experiential, and environmental conditions influenced the development of species-typical behaviors.

Tinbergen ( 1963 ) was among those ethologists who urged for greater developmental analysis of species-typical behaviors, and he included it as one of his four problems in the biological study of organisms, along with causation (mechanism), survival value (function), and evolution. Of these four problems, Tinbergen believed ethologists were especially well suited to study survival value, which he felt had been seriously neglected (Burkhardt, 2005 ).

The questions of survival value coupled with models of population genetics would gain significant momentum in the 1960s and 1970s in England and the United States with the rise of behavioral ecology and sociobiology (Griffiths, 2008 ). But because these new fields seemed to promote some kind of genetic determinism in behavioral development, they were met with much resistance and reignited a new round of nature–nurture debates in the 1970s (see Segerstrale, 2000 ).

However, not all ethologists abandoned the instinct concept. Lorenz, in particular, continued to defend the division between nature and nurture. Rather than speaking of native and acquired behaviors, Lorenz later spoke of two different sources of information for behavior (innate/genetic vs. acquired/environmental), which was more a subtle shift in language than it was an actual change in theory, as Lehrman later pointed out.

Some ethologists followed Lorenz’s lead and continued to maintain more of a traditional delineation between instinct and learning. Their alternative synthesis viewed learning as instinctive (Gould & Marler, 1987 ). They proposed that animals have evolved domain-specific “instincts to learn” that result from the its genetic predispositions and innate knowledge. To support the idea of instincts for learning, ethologists pointed to traditional ethological findings (on imprinting and birdsong learning), but they also drew from the growing body of work in experimental psychology that seemed to indicate certain types of biological effects on learning.

Biological Constraints and Preparedness

While ethology was spreading in Europe in the 1930s–1950s, behaviorism reigned in the United States. Just as ethologists were confronted with including a greater role of nurture in their studies, behaviorists were challenged to consider a greater role of nature.

Behaviorists assumed there to be some behavioral innateness (e.g., fixed action patterns, unconditioned reflexes, primary reinforcers and drives). But because behaviorists focused on learning, they tended to study animals in laboratory settings using biologically (or ecologically) irrelevant stimuli and responses to minimize any role of instinct (Johnston, 1981 ). It was widely assumed that these studies would identify general laws of learning that applied to all species regardless of the specific cues, reinforcers, and responses involved.

Challenges to the generality assumption began to accumulate in the 1960s. Some studies pointed to failures that occurred during conditioning procedures. Breland and Breland ( 1961 ), for example, reported that some complex behaviors formed through operant conditioning would eventually become “displaced” by conditioned fixed action patterns in a phenomenon they called “instinctive drift.” Studies of taste-aversion learning (e.g., Garcia & Koelling, 1966 ) also reported the failure of rats to associate certain events (e.g., flavors with shock or audiovisual stimuli with toxicosis).

Other studies were pointing to enhanced learning. In particular, it was found that rats could form strong conditioned taste aversions after only a single pairing between a novel flavor and illness. (This rapid “one trial learning” was a major focus in the research from Niko Tinbergen’s ethological laboratory.) Animals, it seemed, had evolved innate predispositions to form (or not form) certain associations.

In humans, studies of biological constraints on learning were mostly limited to fear conditioning. Evidence indicated that humans conditioned differently to (biologically or evolutionarily) fear-relevant stimuli like pictures of spiders or snakes than to fear-irrelevant stimuli like pictures of mushrooms or flowers (Ohman, Fredrikson, Hugdahl, & Rimmö, 1976 ).

These findings and others were treated as a major problem in learning theory and led to calls for a new framework to study learning from a more biologically oriented perspective that integrated the evolutionary history and innate predispositions of the species. These predispositions were described as biological “constraints” on, “preparedness,” or “adaptive specializations” for learning, all of which were consistent with the “instincts to learn” framework proposed by ethologists.

By the 1980s it was becoming clear that the biological preparedness/constraint view of learning suffered some limitations. For example, what constraints count as “biological” was questioned. It was well established that there were general constraints on learning associated with the intensity, novelty, and timing of stimuli. But, arbitrarily it seemed, these constraints were not classified as “biological” (Domjan & Galef, 1983 ). Other studies of “biological constraints” found that 5- and 10-day old rats readily learned to associated a flavor with shock (unlike in adults), but (like in adults) such conditioning was not found in 15-day-old rats (Hoffman & Spear, 1988 ). In other words, the constraint on learning was not present in young rats but developed later in life, suggesting a possible role of experience in bringing about the adult-like pattern.

Attempts to synthesize these alternatives led to numerous calls for more ecologically oriented approaches to learning not unlike the synthesis between ethology and comparative psychology in the 1960s. All ecological approaches to learning proposed that learning should be studied in the context of “natural” (recurrent and species-typical) problems that animals encounter (and have evolved to encounter) using ecologically meaningful stimuli and responses. Some argued (e.g., Johnston, 1981 ) that studies of learning should take place within the larger context of studying how animals develop and adapt to their surround. Others (Domjan & Galef, 1983 ) pointed to more of a comparative approach in studying animal learning in line with behavioral ecology that takes into account how learning can be influenced by the possible selective pressures faced by each species. Still, how to synthesize biological constraints (and evolutionary explanations) on learning with a general process approach remains a source of tension in experimental psychology.

Nativism in Mind: Innate Ideas

Nativism and empiricism in philosophy.

In the philosophy of mind, nature–nurture debates are voiced as debates between nativists and empiricists. Nativism is a philosophical position that holds that our minds have some innate (a priori to experience) knowledge, concepts, or structure at the very start of life. Empiricism, in contrast, holds that all knowledge derives from our experiences in the world.

However, rarely (if ever) were there pure nativist or empiricist positions, but the positions bespeak a persistent tension. Empiricists tended to eschew innateness and promote a view of the mental content that is built by general mechanisms (e.g., association) operating on sensory experiences, whereas nativists tend to promote a view of mind that contains domain-specific, innate processes and/or content (Simpson, Carruthers, Laurence, & Stich, 2005 ). Although the tension about mental innateness would loosen as empiricism gained prominence in philosophy and science, the strain never went away and would intensify again in the 20th century .

Nativism in 20th Century Psychology: The Case of Language Development

In the first half of the 20th century , psychologists generally assumed that knowledge was gained or constructed through experience with the world. This is not to say that psychologists did not assume some innate knowledge. The Swiss psychologist Jean Piaget, for example, believed infants enter the world with some innate knowledge structures, particularly as they relate to early sensory and motor functioning (see Piaget, 1971 ). But the bulk of his work dealt with the construction of conceptual knowledge as children adapt to their worlds. By and large, there were no research programs in psychology that sought to identify innate factors in human knowledge and cognition until the 1950s (Samet & Zaitchick, 2017 )

An interest in psychological nativism was instigated in large part by Noam Chomsky’s ( 1959 ) critique of B. F. Skinner’s book on language. To explain the complexity of language, he argued, we must view language as the knowledge and application of grammatical rules. He went on to claim that the acquisition of these rules could not be attributed to any general-purpose, learning process (e.g., reinforcement). Indeed, language acquisition occurs despite very little explicit instruction. Moreover, language is special in terms of its complexity, ease, and speed of acquisition by children and in its uniqueness to humans. Instead, he claimed that our minds innately contain some language-specific knowledge that kick-starts and promotes language acquisition. He later claimed this knowledge can be considered some sort of specialized mental faculty or module he called the “language acquisition device” (Chomsky, 1965 ) or what Pinker ( 1995 ) later called the “language instinct.”

To support the idea of linguistic nativism, Chomsky and others appealed to the poverty of the stimulus argument. In short, this argument holds that our experiences in life are insufficient to explain our knowledge and abilities. When applied to language acquisition, this argument holds children’s knowledge of language (grammar) goes far beyond the limited, and sometimes broken, linguistic events that children directly encounter. Additional evidence for nativism drew upon the apparent maturational quality of language development. Despite wide variations in languages and child-rearing practices across the world, the major milestones in language development appear to unfold in children in a universal sequence and timeline, and some evidence suggested a critical period for language acquisition.

Nativist claims about language sparked intense rebuttals by empiricist-minded psychologists and philosophers. Some of these retorts tackled the logical limitations of the poverty of stimulus argument. Others pointed to the importance of learning and social interaction in driving language development, and still others showed that language (grammatical knowledge) may not be uniquely human (see Tomasello, 1995 , for review). Nativists, in due course, provided their own rebuttals to these challenges, creating a persistent tension in psychology.

Extending Nativism Beyond Language Development

In the decades that followed, nativist arguments expanded beyond language to include cognitive domains that dealt with understanding the physical, psychological, and social worlds. Developmental psychologists were finding that infants appeared to be much more knowledgeable in cognitive tasks (e.g., on understanding object permanence) and skillful (e.g., in imitating others) than had previously been thought, and at much younger ages. Infants also showed a variety of perceptual biases (e.g., preference for face-like stimuli over equally complex non-face-like stimuli) from very early on. Following the standard poverty of the stimulus argument, these findings were taken as evidence that infants enter the world with some sort of primitive, innate, representational knowledge (or domain-specific neural mechanisms) that constrains and promotes subsequent cognitive development. The nature of this knowledge (e.g., as theories or as core knowledge), however, continues to be debated (Spelke & Kinzler, 2007 ).

Empiricist-minded developmental psychologists responded by demonstrating shortcomings in the research used to support nativist claims. For example, in studies of infants’ object knowledge, the behavior of infants (looking time) in nativist studies could be attributed to relatively simple perceptual processes rather than to the infants’ conceptual knowledge (Heyes, 2014 ). Likewise, reports of human neonatal imitation not only suffered from failures to replicate but could be explained by simpler mechanisms (e.g., arousal) than true imitation (Jones, 2017 ). Finally, studies of perceptual preferences found in young infants, like newborn preferences for face-like stimuli, may not be specific preferences for faces per se but instead may reflect simpler, nonspecific perceptual biases (e.g., preferences for top-heavy visual configurations and congruency; Simion & Di Giorgio, 2015 ).

Other arguments from empiricist-minded developmental psychologists focused on the larger rationale for inferring innateness. Even if it is conceded that young infants, like two-month-olds, or even two-day-olds, display signs of conceptual knowledge, there is no good evidence to presume the knowledge is innate. Their knowledgeable behaviors could still be seen as resulting from their experiences (many of which may be nonobvious to researchers) leading up to the age of testing (Spencer et al., 2009 ).

In the 21st century , there is still no consensus about the reality, extensiveness, or quality of mental innateness. If there is innate knowledge, can experience add new knowledge or only expand the initial knowledge? Can the doctrine of innate knowledge be falsified? There are no agreed-upon answers to these questions. The recurring arguments for and against mental nativism continue to confound developmental psychologists.

Maturation Theory

The emergence of bodily changes and basic behavioral skills sometimes occurs in an invariant, predictable, and orderly sequence in a species despite wide variations in rearing conditions. These observations are often attributed to the operation of an inferred, internally driven, maturational process. Indeed, 21st-century textbooks in psychology commonly associate “nature” with “maturation,” where maturation is defined as the predetermined unfolding of the individual from a biological or genetic blueprint. Environmental factors play a necessary, but fundamentally supportive, role in the unfolding of form.

Preformationism Versus Epigenesis in the Generation of Form

The embryological generation of bodily form was debated in antiquity but received renewed interest in the 17th century . Following Aristotle, some claimed that embryological development involved “epigenesis,” defined as the successive emergence of form from a formless state. Epigenesists, however, struggled to explain what orchestrated development without appealing to Aristotelean souls. Attempts were made to invoke to natural causes like physical and chemical forces, but, despite their best efforts, the epigenesists were forced to appeal to the power of presumed, quasi-mystical, vitalistic forces (entelechies) that directed development.

The primary alternative to epigenesis was “preformationism,” which held that development involved the growth of pre-existing form from a tiny miniature (homunculus) that formed immediately after conception or was preformed in the egg or sperm. Although it seems reasonable to guess that the invention and widespread use of the microscope would immediately lay to rest any claim of homuncular preformationism, this was not the case. To the contrary, some early microscopists claimed to see signs of miniature organisms in sperm or eggs, and failures to find these miniatures were explained away (e.g., the homunculus was transparent or deflated to the point of being unrecognizable). But as microscopes improved and more detailed observations of embryological development were reported in the late 18th and 19th centuries , homuncular preformationism was finally refuted.

From Preformationism to Predeterminism

Despite the rejection of homuncular preformationism, preformationist appeals can be found throughout the 19th century . One of the most popular preformationist theories of embryological development was put forth by Ernst Haeckel in the 1860s (Gottlieb, 1992 ). He promoted a recapitulation theory (not original to Haeckel) that maintained that the development of the individual embryo passes through all the ancestral forms of its species. Ontogeny was thought to be a rapid, condensed replay of phylogeny. Indeed, for Haeckel, phylogenesis was the mechanical cause of ontogenesis. The phylogenetic evolution of the species created the maturational unfolding of embryonic form. Exactly how this unfolding takes place was less important than its phylogenetic basis.

Most embryologists were not impressed with recapitulation theory. After all, the great embryologist Karl Ernst von Baer ( 1792–1876 ) had refuted strict recapitulation decades earlier. Instead, there was greater interest in how best to explain the mechanical causes of development ushering in a new “experimental embryology.” Many experimental embryologists followed the earlier epigenesists by discussing vitalistic forces operating on the unorganized zygote. But it soon became clear that the zygote was structured, and many people believed the zygote contained special (unknown) substances that specified development. Epigenesis-minded experimental embryologists soon warned that the old homuncular preformationism was being transformed into a new predetermined preformationism.

As a result, the debates between preformationism and epigenesis were reignited in experimental embryology, but the focus of these debates shifted to the various roles of nature and nurture during development. More specifically, research focused on the extent to which early cellular differentiation was predetermined by factors internal to cells like chromosomes or cytoplasm (preformationism, nature) or involved factors (e.g., location) outside of the cell (epigenesis, nurture). The former emphasized reductionism and developmental programming, whereas the latter emphasized some sort of holistic, regulatory system responsive to internal and external conditions. The tension between viewing development as predetermined or “epigenetic” persists into the 21st century .

Preformationism gained momentum in the 20th century following the rediscovery of Mendel’s studies of heredity and the rapid rise of genetics, but not because of embryological research on the causes of early differentiation. Instead, preformationism prevailed because it seemed embryological research on the mechanisms of development could be ignored in studies of hereditary patterns.

The initial split between heredity and development can be found in Galton’s speculations but is usually attributed to Weismann’s germ-plasm theory. Weismann’s barrier seemed to posit that the germinal determinants present at conception would be the same, unaltered determinants transmitted during reproduction. This position, later dubbed as “Weismannism,” was ironically not one promoted by Weismann. Like nearly all theorists in the 19th century , he viewed the origins of variation and heredity as developmental phenomena (Amundson, 2005 ), and he claimed that the germ-plasm could be directly modified in the lifetime of the organism by environmental (e.g., climactic and dietary) conditions (Winther, 2001 ). Still, Weismann’s theory treated development as a largely predetermined affair driven by inherited, germinal determinants buffered from most developmental events. As such, it helped set the stage for a more formal divorce between heredity and development with the rise of Mendelism in the early 20th century .

Mendel’s theory of heredity was exceptional in how it split development from heredity (Amundson, 2005 ). More so than in Weismann’s theory, Mendel’s theory assumed that the internal factors that determine form and are transmitted across generations remain unaltered in the lifetime of the organism. To predict offspring outcomes, one need only know the combination of internal factors present at conception and their dominance relations. Exactly how these internal factors determined form could be disregarded. The laws of hereditary transmission of the internal factors (e.g., segregation) did not depend on the development or experiences of the organism or the experiences the organism’s ancestors. Thus the experimental study of heredity (i.e., breeding) could proceed without reference to ancestral records or embryological concerns (Amundson, 2000 ). By the mid-1920s, the Mendelian factors (now commonly called “genes”) were found to be structurally arranged on chromosomes, and the empirical study of heredity (transmission genetics) was officially divorced from studies of development.

The splitting of heredity and development found in Mendel’s and Weismann’s work met with much resistance. Neo-Lamarckian scientists, especially in the United States (Cook, 1999 ) and France (Loison, 2011 ), sought unsuccessfully to experimentally demonstrate the inheritance of acquired characteristics into the 1930s.

In Germany during the 1920s and 1930s, resistance to Mendelism dealt with the chromosomal view of Mendelian heredity championed by American geneticists who were narrowly focused on studying transmission genetics at the expense of developmental genetics. German biologists, in contrast, were much more interested in the broader roles of genes in development (and evolution). In trying to understand how genes influence development, particularly of traits of interest to embryologists, they found the Mendelian theory to be lacking. In the decades between the world wars, German biologists proposed various expanded views of heredity that included some form of cytoplasmic inheritance (Harwood, 1985 ).

Embryologists resisted the preformationist view of development throughout the early to mid- 20th century , often maintaining no divide between heredity and development, but their objections were overshadowed by genetics and its eventual synthesis with evolutionary theory. Consequently, embryological development was treated by geneticists and evolutionary biologists as a predetermined, maturational process driven by internal, “genetic” factors buffered from environmental influence.

Maturation Theory in Psychology

Maturation theory was applied to behavioral development in the 19th century in the application of Haeckel’s recapitulation theory. Some psychologists believed that the mental growth of children recapitulated the history of the human race (from savage brute to civilized human). With this in mind, many people began to more carefully document child development. Recapitulationist notions were found in the ideas of many notable psychologists in the 19th and early 20th centuries (e.g., G. S. Hall), and, as such, the concept played an important role in the origins of developmental psychology (Koops, 2015 ). But for present purposes what is most important is that children’s mental and behavioral development was thought to unfold via a predetermined, maturational process.

With the growth of genetics, maturational explanations were increasingly invoked to explain nearly all native and hereditary traits. As the instinct concept lost value in the 1920s, maturation theory gained currency, although the shift was largely a matter of semantics. For many psychologists, the language simply shifted from “instinct versus learning” to “maturation versus practice/experience” (Witty & Lehman, 1933 ).

Initial lines of evidence for maturational explanations of behavior were often the same as those that justified instinct and native traits, but new embryological research presented in the mid-1920s converged to show support for strict maturational explanations of behavioral development. In these experiments (see Wyman, 2005 , for review), spanning multiple laboratories, amphibians (salamanders and frogs) were exposed to drugs that acted as anesthetics and/or paralytics throughout the early stages of development, thus reducing sensory experience and/or motor practice. Despite the reduced sensory experiences and being unable to move, these animals showed no delays in the onset of motor development once the drugs wore off.

This maturational account of motor development in amphibians fit well with contemporaneous studies of motor development in humans. The orderly, invariant, and predictable (age-related) sequential appearance of motor skills documented in infants reared under different circumstances (in different countries and across different decades) was seen as strong evidence for a maturational account. Additional evidence was reported by Arnold Gessell and Myrtle McGraw, who independently presented evidence in the 1920s to show that the pace and sequence of motor development in infancy were not altered by special training experiences. Although the theories of these maturation theorists were more sophisticated when applied to cognitive development, their work promoted a view in which development was primarily driven by neural maturation rather than experience (Thelen, 2000 ).

Critical and Sensitive Periods

As the maturation account of behavioral development gained ground, it became clear that environmental input played a more informative role than had previously been thought. Environmental factors were found to either disrupt or induce maturational changes at specific times during development. Embryological research suggested that there were well-delineated time periods of heightened sensitivity in which specific experimental manipulations (e.g., tissue transplantations) could induce irreversible developmental changes, but the same manipulation would have no effect outside of that critical period.

In the 1950s–1960s a flurry of critical period effects were reported in birds and mammals across a range of behaviors including imprinting, attachment, socialization, sensory development, bird song learning, and language development (Michel & Tyler, 2005 ). Even though these findings highlighted an important role of experience in behavioral development, evidence of critical periods was usually taken to imply some rigid form of biological determinism (Oyama, 1979 ).

As additional studies were conducted on critical period effects, it became clear that many of the reported effects were more gradual, variable, experience-dependent, and not necessarily as reversible as was previously assumed. In light of these reports, there was a push in the 1970s (e.g., Connolly, 1972 ) to substitute “sensitive period” for “critical period” to avoid the predeterminist connotations associated with the latter and to better appreciate that these periods simply describe (not explain) certain temporal aspects of behavioral development. As a result, a consensus emerged that behaviors should not be attributed to “time” or “age” but to the developmental history and status of the animal under investigation (Michel & Tyler, 2005 ).

Heredity and Genetics

In the decades leading up to and following the start of the 20th century , it was widely assumed that many psychological traits (not just instincts) were inherited or “due to heredity,” although the underlying mechanisms were unknown. Differences in intelligence, personality, and criminality within and between races and sexes were largely assumed to be hereditary and unalterable by environmental intervention (Gould, 1996 ). The evidence to support these views in humans was often derived from statistical analyses of how various traits tended to run in families. But all too frequently, explanations of data were clouded by pre-existing, hereditarian assumptions.

Human Behavioral Genetics

The statistical study of inherited human (physical, mental, and behavioral) differences was pioneered by Galton ( 1869 ). Although at times Galton wrote that nature and nurture were so intertwined as to be inseparable, he nevertheless devised statistical methods to separate their effects. In the 1860s and 1870s, Galton published reports purporting to show how similarities in intellect (genius, talent, character, and eminence) in European lineages appeared to be a function of degree of relatedness. Galton considered, but dismissed, environmental explanations of his data, leading him to confirm his belief that nature was stronger than nurture.

Galton also introduced the use of twin studies to tease apart the relative impact of nature versus nurture, but the twin method he used was markedly different from later twin studies used by behavioral geneticists. Galton tracked the life history of twins who were judged to be very similar or very dissimilar near birth (i.e., by nature) to test the power of various postnatal environments (nurture) that might make them more or less similar over time. Here again, Galton concluded that nature overpowers nurture.

Similar pedigree (e.g., the Kallikak study; see Zenderland, 2001 ) and twin studies appeared in the early 1900s, but the first adoption study and the modern twin method (which compares monozygotic to dizygotic twin pairs) did not appear until the 1920s (Rende, Plomin, & Vandenberg, 1990 ). These reports led to a flurry of additional work on the inheritance of mental and behavioral traits over the next decade.

Behavioral genetic research peaked in the 1930s but rapidly lost prominence due in large part to its association with the eugenics movement (spearheaded by Galton) but also because of the rise and eventual hegemony of behaviorism and the social sciences in the United States. Behavioral genetics resurged in the 1960s with the rising tide of nativism in psychology, and returned to its 1930s-level prominence in the 1970s (McGue & Gottesman, 2015 ).

The resurgence brought with a new statistical tool: the heritability statistic. The origins of heritability trace back to early attempts to synthesize Mendelian genetics with biometrics by Ronald Fisher and others. This synthesis ushered in a new field of quantitative genetics and it marked a new way of thinking about nature and nurture. The shift was to no longer think about nature and nurture as causes of traits in individuals but as causes of variation in traits between populations of individuals. Eventually, heritability came to refer to the amount of variance in a population sample that could be statistically attributed to genetic variation in that sample. Kinship (especially twin) studies provided seemingly straightforward ways of partitioning variation in population trait attributes into genetic versus environmental sources.

Into the early 21st century , hundreds of behavioral genetic studies of personality, intelligence, and psychopathology were reported. With rare exceptions, these studies converge to argue for a pervasive influence of genetics on human psychological variation.

These studies have also fueled much controversy. Citing in part behavioral genetic research, the educational psychologist Arthur Jensen ( 1969 ) claimed that the differences in intelligence and educational achievement in the United States between black and white students appeared to have a strong genetic basis. He went on to assume that because these racial differences appeared hereditary, they were likely impervious to environmental (educational) intervention. His article fanned the embers of past eugenics practices and ignited fiery responses (e.g., Hirsch, 1975 ). The ensuing debates not only spawned a rethinking of intelligence and how to measure it, but they ushered in a more critical look at the methods and assumptions of behavioral genetics.

Challenges to Behavioral Genetics

Many of the early critiques of behavioral genetics centered on interpreting the heritability statistic commonly calculated in kinship (family, twin, and adoption) studies. Perhaps more so than any other statistic, heritability has been persistently misinterpreted by academics and laypersons alike (Lerner, 2002 ). Contrary to popular belief, heritability tells us nothing about the relative impact of genetic and environmental factors on the development of traits in individuals. It deals with accounting for trait variation between people, not the causes of traits within people. As a result, a high heritability does not indicate anything about the fixity of traits or their imperviousness to environmental influence (contra Jensen), and a low heritability does not indicate an absence of genetic influence on trait development. Worse still, heritability does not even indicate anything about the role of genetics in generating the differences between people.

Other challenges to heritability focused not on its interpretation but on its underlying computational assumptions. Most notably, heritability analyses assume that genetic and environmental contributions to trait differences are independent and additive. The interaction between genetic and environmental factors were dismissed a priori in these analyses. Studies of development, however, show that no factor (genes, hormones, parenting, schooling) operates independently, making it impossible to quantify how much of a given trait in a person is due to any causal factor. Thus heritability analyses are bound to be misleading because they are based on biologically implausible and logically indefensible assumptions about development (Gottlieb, 2003 ).

Aside from heritability, kinship studies have been criticized for not being able to disentangle genetic and environmental effects on variation. It had long been known that that in family (pedigree) studies, environmental and genetic factors are confounded. Twin and adoption studies seemed to provide unique opportunities to statistically disentangle these effects, but these studies are also deeply problematic in assumptions and methodology. There are numerous plausible environmental reasons for why monozygotic twin pairs could resemble each other more than dizygotic twin pairs or why adoptive children might more closely resemble their biological than their adoptive parents (Joseph & Ratner, 2013 ).

A more recent challenge to behavioral genetics came from an unlikely source. Advances in genomic scanning in the 21st century made it possible in a single study to correlate thousands of genetic polymorphisms with variation in the psychological profiles (e.g., intelligence, memory, temperament, psychopathology) of thousands of people. These “genome-wide association” studies seemed to have the power and precision to finally identify genetic contributions to heritability at the level of single nucleotides. Yet, these studies consistently found only very small effects.

The failure to find large effects came to be known as the “missing heritability” problem (Maher, 2008 ). To account for the missing heritability, some behavioral geneticists and molecular biologists asserted that important genetic polymorphisms remain unknown, they may be too rare to detect, and/or that current studies are just not well equipped to handle gene–gene interactions. These studies were also insensitive to epigenetic profiles (see the section on Behavioral Epigenetics), which deal with differences in gene expression. Even when people share genes, they may differ in whether those genes get expressed in their lifetimes.

But genome-wide association studies faced an even more problematic issue: Many of these studies failed to replicate (Lickliter & Honeycutt, 2015 ). For those who viewed heritability analyses as biologically implausible, the small effect sizes and failures to replicate in genome-wide association studies were not that surprising. The search for independent genetic effects was bound to fail, because genes simply do not operate independently during development.

Behavioral Epigenetics

Epigenetics was a term coined in the 1940s by the developmental biologist Conrad Waddington to refer to a new field of study that would examine how genetic factors interact with local environmental conditions to bring about the embryological development of traits. By the end of the 20th century , epigenetics came to refer to the study of how nongenetic, molecular mechanisms physically regulate gene expression patterns in cells and across cell lineages. The most-studied mechanisms involve organic compounds (e.g., methyl-groups) that physically bind to DNA or the surrounding proteins that package DNA. The addition or removal of these compounds can activate or silence gene transcription. Different cell types have different, stable epigenetic markings, and these markings are recreated during cell division so that cells so marked give rise to similar types of cells. Epigenetic changes were known to occur during developmental periods of cellular differentiation (e.g., during embryogenesis), but not until 2004 was it discovered that these changes can occur at other periods in the life, including after birth (Roth, 2013 )

Of interest to psychologists were reports that different behavioral and physiological profiles (e.g., stress reactivity) of animals were associated with different epigenetic patterns in the nervous system (Moore, 2015 ). Furthermore, these different epigenetic patterns could be established or modified by environmental factors (e.g., caregiving practices, training regimes, or environmental enrichment), and, under certain conditions, they remain stable over long periods of time (from infancy to adulthood).

Because epigenetic research investigates the physical interface between genes and environment, it represents an exciting advance in understanding the interaction of nature and nurture. Despite some warnings that the excitement over behavioral epigenetic research may be premature (e.g., Miller, 2010 ), for many psychologists, epigenetics underscores how development involves both nature and nurture.

For others, what is equally exciting is the additional evidence epigenetics provides to show that the genome is an interactive and regulated system. Once viewed as the static director of development buffered from environment influence, the genome is better described as a developing resource of the cell (Moore, 2015 ). More broadly, epigenetics also points to how development is not a genetically (or biologically) predetermined affair. Instead, epigenetics provides additional evidence that development is a probabilistic process, contingent upon factors internal and external to the organism. In this sense, epigenetics is well positioned to help dissolve the nature–nurture dichotomy.

Beyond Nature–Nurture

In the final decades of the 20th century , a position was articulated to move beyond the dichotomous nature–nurture framework. The middle-ground position on nature–nurture did not seem up to the task of explaining the origins of form, and it brought about more confusion than clarity. The back-and-forth (or balanced) pendulum between nature- and nurture-based positions throughout history had only gone in circles. Moving forward would require moving beyond such dichotomous thinking (Johnston, 1987 ).

The anti-dichotomy position, referred to as the Developmentalist tradition, was expressed in a variety of systems-based, metatheoretical approaches to studying development, all of which extended the arguments against nature–nurture expressed earlier by Kuo and Lehrman. The central problem with all nativist claims according to Developmentalists is a reliance on preformationism (or predeterminism).

The problem with preformationism, they argue, besides issues of evidence, is that it is an anti-developmental mindset. It presumes the existence of the very thing(s) one wishes to explain and, consequently, discourages developmental analyses. To claim that some knowledge is innate effectively shuts down research on the developmental origins of that knowledge. After all, why look for the origins of conceptual knowledge if that knowledge is there all along? Or why search for any experiential contributions to innate behaviors if those behaviors by definition develop independently of experience? In the words of Developmentalists Thelen and Adolph ( 1992 ), nativism “leads to a static science, with no principles for understanding change or for confronting the ultimate challenge of development, the source of new forms in structure and function” (p. 378).

A commitment to maturational theory is likely one of the reasons why studies of motor development remained relatively dormant for decades following its heyday in the 1930–1940s (Thelen, 2000 ). Likewise, a commitment to maturational theory also helps explain the delay in neuroscience to examine how the brain physically changes in response to environmental conditions, a line of inquiry that only began in the 1960s.

In addition to the theoretical pitfalls of nativism, Developmentalists point to numerous studies that show how some seemingly native behaviors and innate constraints on learning are driven by the experiences of animals. For example, the comparative psychologist Gilbert Gottlieb ( 1971 ) showed that newly hatched ducklings display a naïve preference for a duck maternal call over a (similarly novel) chicken maternal call (Gottlieb, 1971 ), even when duck embryos were repeatedly exposed to the chicken call prior to hatching (Gottlieb, 1991 ). It would be easy to conclude that ducklings have an innate preference to approach their own species call and that they are biologically constrained (contraprepared) in learning a chicken call. However, Gottlieb found that the naïve preference for the duck call stemmed from exposure to the duck embryos’ own (or other) vocalizations in the days before hatching (Gottlieb, 1971 ). Exposure to these vocalizations not only made duck maternal calls more attractive, but it hindered the establishment of a preference for heterospecific calls. When duck embryos were reared in the absence of the embryonic vocalizations (by devocalizing embryos in ovo ) and exposed instead to chicken maternal calls, the newly hatched ducklings preferred chicken over duck calls (Gottlieb, 1991 ). These studies clearly showed how seemingly innate, biologically based preferences and constraints on learning derived from prenatal sensory experiences.

For Developmentalists, findings like these suggest that nativist explanations of any given behavior are statements of ignorance about how that behavior actually develops. As Kuo and Lehrman made clear, nativist terms are labels, not explanations. Although such appeals are couched in respectable, scientific language (e.g., “X is due to maturation, genes, or heredity”), they argue it would be more accurate simply to say that “We don’t know what causes X” or that “X is not due to A, B, or C.” Indeed, for Developmentalists, the more we unpack the complex dynamics about how traits develop, the less likely we are to use labels like nature or nurture (Blumberg, 2005 ).

On the other hand, Developmentalists recognize that labeling a behavior as “learned” also falls short as an explanatory construct. The empiricist position that knowledge or behavior is learned does not adequately take into account that what is learned and how easily something is learned depends on (a) the physiological and developmental status of the person, (b) the nature of the surrounding physical and social context in which learning takes place, and the (c) experiential history of the person. The empiricist tendency to say “X is learned or acquired through experience” can also short-circuit developmental analyses in the same way as nativist claims.

Still, Developmentalists appreciate that classifying behaviors can be useful. For example, the development of some behaviors may be more robust, reliably emerging across a range of environments and/or remaining relatively resistant to change, whereas others are more context-specific and malleable. Some preferences for stimuli require direct experience with those stimuli. Other preferences require less obvious (indirect) types of experiences. Likewise, it can still be useful to describe some behaviors in the ways shown in Table 1 . Developmentalists simply urge psychologists to resist the temptation to treat these behavioral classifications as implying different kinds of explanations (Johnston, 1987 ).

Rather than treat nature and nurture as separate developmental sources of causation (see Figure 1 ), Developmentalists argue that a more productive way of thinking about nature–nurture is to reframe the division as that between product and process (Lickliter & Honeycutt, 2015 ). The phenotype or structure (one’s genetic, epigenetic, anatomical, physiological, behavioral, and mental profile) of an individual at any given time can be considered one’s “nature.” “Nurture” then refers to the set of processes that generate, maintain, and transform one’s nature (Figure 2 ). These processes involve the dynamic interplay between phenotypes and environments.

Figure 2. The developmentalist alternative view of nature–nurture as product–process. Developmentalists view nature and nurture not as separate sources of causation in development (see Figure 1 ) but as a distinction between process (nurture) and product (nature).

It is hard to imagine any set of findings that will end debates about the roles of nature and nurture in human development. Why? First, more so than other assumptions about human development, the nature–nurture dichotomy is deeply entrenched in popular culture and the life sciences. Second, throughout history, the differing positions on nature and nurture were often driven by other ideological, philosophical, and sociopolitical commitments. Thus the essential source of tension in debates about nature–nurture is not as much about research agendas or evidence as about basic differences in metatheoretical positions (epistemological and ontological assumptions) about human behavior and development (Overton, 2006 ).

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Nature versus Nurture Debate in Psychology by Hunter Honeycutt LAST REVIEWED: 12 January 2023 LAST MODIFIED: 12 January 2023 DOI: 10.1093/obo/9780199828340-0305

The nature-nurture dichotomy is a long-standing and pervasive framework for thinking about the causal influences believed to be operating during individual development. In this dichotomy, nature refers to factors (e.g., genes, genetic programs, and/or biological blueprints) or forces (e.g., heredity and/or maturation) inherent to the individual that predetermine the development of form and function. Nurture generally refers to all the remaining, typically “external,” causal factors (e.g., physical and social conditions) and processes (e.g., learning and experience) that influence development. The nature versus nurture debate in psychology deals with disagreements about the extent to which the development of traits in humans and animals reflects the relative influence of nature and nurture. It is commonly stated that psychologists have moved on from asking whether traits (or variation in traits) develop from nature or nurture, to recognize instead that both nature and nurture work together or “interact” to produce outcomes, although exactly how to view the interaction is a matter of much debate. While acknowledging the interaction of nature and nurture, one’s theoretical models and research focus might emphasize the prominence of one over the other. Thus, nativists focus more on the importance of innate factors or forces operating on development, whereas empiricists focus more on experiential or environmental factors. However, not everyone finds value in thinking about development in terms of nature and nurture. By the middle of the twentieth century, some psychologists, biologists, and philosophers began to view nature-nurture as a conceptually deficient and biologically implausible dichotomy that oversimplifies the dynamics of behavior and development. Such people espouse some variant of “developmental systems theory” and seek to eliminate or otherwise fuse the nature-nurture division.

The works in this section are mostly trade books that provide general introductions to the nature-nurture debate across a variety of topical areas in psychology, all of which would be suitable for use in classes with undergraduate students at all levels. Goldhaber 2012 contrasts four popular perspectives on the nature-nurture issue and would be a good place to start for anyone unfamiliar with the nature-nurture debate in psychology. Nativist perspectives are represented by Pinker 2002 , Plomin 2018 , and Vallortigara 2021 . An empiricist-leaning position on behavior development is put forth in Schneider 2012 . Developmental systems theory is promoted in Blumberg 2005 and Moore 2002 . Two edited books are included and both are better suited for advanced undergraduate- or graduate-level students. The first edited book, Coll, et al. 2013 , focuses on the nature-nurture issue across a range of topics and perspectives in psychology. The other, Mayes and Lewis 2012 , presents empiricist (or environmentalist) perspectives on child development.

Bateson, P. 2017. Behaviour, development and evolution . Cambridge, UK: OpenBook Publishers.

DOI: 10.11647/OBP.0097

Written by a distinguished ethologist who draws extensively from his work on animal behavior, this book argues that the nature-nurture division is neither valid nor helpful in capturing the complex system of factors that influence behavioral development. Topics include imprinting and attachment, parent-offspring relations, the influence of early-life experiences on later-life outcomes, problems with genetic determinism, and the role of behavior in evolutionary change.

Blumberg, M. S. 2005. Basic instinct: The genesis of novel behavior . New York: Thunder’s Mouth Press.

Consistent with developmental systems theory, Blumberg presents an overview of the conceptual and empirical limitations of nativism in explanations of behavioral and neural development in animals and cognitive development in humans.

Coll, C. G., E. L. Bearer, and R. M. Lerner, eds. 2013. Nature-nurture: The complex interplay of genetic and environmental influences on human behavior and development . New York: Psychology Press.

The contents of this edited volume are almost entirely original works with commentary that span multiple disciplines (psychology, biology, economics, philosophy) and multiple perspectives (behavioral genetics and developmental systems theory) on the nature-nurture issue.

Goldhaber, D. 2012. The nature-nurture debates: Bridging the gap . Cambridge, UK: Cambridge Univ. Press.

DOI: 10.1017/CBO9781139022583

Goldhaber reviews four major perspectives (behavior genetics, environmentalism, evolutionary psychology, and developmental systems theory) on the nature-nurture issue. He argues we should reject reductionist views based on either genetic determinism or environmental determinism in favor of more holistic, interactionist approaches.

Mayes, L. C., and M. Lewis, eds. 2012. The Cambridge handbook of environment in human development . Cambridge, UK: Cambridge Univ. Press.

This handbook explores a wide variety of ways in which the environment influences child development. Chapters cover conceptual frameworks and methodological issues in thinking about and studying environmental influences as well reviewing ways in which environmental contexts and systems influence specific aspects of child development.

Moore, D. S. 2002. The dependent gene: The fallacy of nature vs. nurture . New York: Henry Holt.

This book provides an introduction to the developmental systems theory take on the nature-nurture issue particularly as it relates to genetic determinism, heritability and heredity.

Pinker, S. 2002. The blank slate: The modern denial of human nature . New York: Viking.

In this best-selling book, Pinker draws on evidence from behavioral genetics, evolutionary psychology, and cognitive psychology to argue for a nativist position concerning human nature.

Plomin, R. 2018. Blueprint: How DNA makes us who we are . Cambridge, MA: MIT Press.

Plomin reviews traditional and more modern evidence from behavioral genetics to argue that genes are the primary factor in bringing about psychological differences between people. Moreover, he argues that many “environmental” factors operating on development are themselves strongly influenced by genetic differences.

Schneider, S. M. 2012. The science of consequences: How they affect genes, change the brain, and impact our world . Amherst, NY: Prometheus Books.

Schneider presents a view grounded in behavior analysis to argue for the critical role that the consequences of genetic activity, neural activity, and behavioral activity play in individual development. While emphasizing environmental (or experiential) factors influencing development, this book also highlights the systemic and interactive nature of developmental systems across multiple levels of analysis.

Vallortigara, G. 2021. Born knowing: Imprinting and the origins of knowledge . Cambridge, MA: MIT Press.

DOI: 10.7551/mitpress/14091.001.0001

Drawing upon research in comparative cognition and comparative neuroscience, much of it his own, Vallortigara argues that animals, including humans, enter the world with a set of unlearned, innate or instinctive behaviors and neural circuits that bias or predispose subsequent learning and development.

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Nature vs Nurture Examples: Genes or Environment

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The nature versus nurture debate focuses on the question of whether genetic or environmental factors matter most in the course of human development.

What is it that makes you who you are? Some might say that it is your genes that have the greatest influence in controlling your personality and preferences. Others might say that it is your environment and the unique experiences you have had over the course of your life that have a greater role.

In this article, learn more about the nature vs. nurture debate and what research has found about the contributions of genetic and environmental factors.

Table of Contents

What Is the Nature vs Nurture Debate?

The nature vs. nurture debate is often described as one of the big philosophical and scientific questions facing psychologists. So what exactly does this debate mean? Why is it important for understanding the human mind and behavior?  

Let’s start by learning more about each of these factors.

• Nature: This side of the debate argues that genes have the greatest influence over who we are, from the way we look to the way we behave. Genes determine physical traits such as height, eye color, hair color, and face shape, but they can also contribute to other attributes such as your personality traits and cognitive abilities.
• Nurture: This side of the debate argues that environmental variables such as upbringing, individual experiences, and other social relationships play a more important role. Your upbringing, early social interactions, school, and peers all shape who you are and how you behave.

Let’s consider an example. If a student excels at math, is it because they inherited that ability from their parents or because they work hard to learn the subject?

Nature would suggest that they do well because they are genetically inclined to do so, while nature argues that their talent stems from their upbringing and educational background.

History of Nature vs. Nurture

The debate over nature and nurture predates psychology and goes back to the days of the ancient philosophers. In philosophy, this is often referred to as the nativism versus empiricism debate. What do these terms mean and how do they relate to nature and nurture?

The nativist approach suggests that inheritance plays the greatest role in determining characteristics. Nativism proposes that people’s characteristics, both physical and mental, are innate. These are things that are passed down genetically from our ancestors. The nativist approach essentially espouses the nature side of the argument.

Noam Chomsky’s theory of language acquisition is one of the best-known examples of nativism in psychology.  Chomsky suggested that language develops as a result of an innate language acquisition device. He believed that people are able to learn language because they have an innate, hard-wired capacity for what he referred to as universal grammar.

Empiricism represents the nurture side of the debate. The empiricist approach suggests that all learning is the result of experience and environmental factors.

The philosopher John Locke took an empiricist approach and proposed a concept known as tabula rasa, which means “blank slate.” This approach that the mind is essentially that —a blank slate—and that it is through learning and experience that all knowledge, skill, and behavioral patterns are acquired.

Behaviorism is one example of an empirical approach to understanding human behavior. Behaviorists such as John B. Watson and B.F. Skinner believed that all human behavior was the result of conditioning, either classical (associative) or operant ( reinforcement and punishment ).

Watson was famously known for proclaiming that he could train anyone to be anything using the principles of conditioning, regardless of that individual’s genetics and background.

Approaches to Psychology

While few contemporary psychologists take an extreme, hard-lined empiricist or nativist approach, different branches of psychology do sometimes tend to emphasize one influence over the other.

Biological Psychology

Biological psychology, for example, tends to focus more on the nature side of the debate. This area of psychology focuses on how biological factors influence human behavior, so things such as the brain, neurons, and neurotransmitters are of greater interest than external factors.

Behavioral Psychology

Behavioral psychology tends to take the nurture side of the debate, focusing on how environmental factors and learned associations contribute to how people think and act.

Health Psychology

Health psychology is an example of an approach that tends to lie somewhere in the middle. Health psychologists are focused on understanding how both biological and environmental factors contribute and interact to affect an individual’s health.

Nature vs. Nurture Examples

Looking at examples can be helpful to understand why the nature vs nurture debate has been so crucial throughout psychology’s history. The topic is not just an important philosophical debate. It has been critical for understanding what factors influence different aspects of human behavior and has been the source of considerable controversy at times.

Consider the long debate over the factors that influence intelligence. Those on the nature side of the debate suggest that the greatest influence on IQ is inheritance. Some early thinkers such as Francis Galton believed that intelligence could largely be attributed to genetic factors.

Such views have been used to justify discriminatory social policies and attitudes. When some research suggested that some groups of people had lower IQ scores, for example, some researchers interpreted these results to suggest that these individuals scored lower as a result of genetics.

Those taking the nurture side of the debate point out that other factors, including biased test construction, racism, and systemic discrimination impacting educational access and quality, play a more important role.

Inequality, discrimination, and lack of access play a role in shaping how well people perform on intelligence tests and other assessments of educational outcomes.

Gender Differences and Education

Sex differences in school performance and attainment is another area where the debate between the contributions of nature vs nurture comes into play. Girls often perform better on verbal tests but less well on math. As they advance in school, girls also become less likely to enter STEM courses and STEM fields.

Those taking a nature perspective might suggest that girls are inherently less capable in these subjects. Nature advocates, however, would point out that social variables, including gender stereotypes and discrimination, have a greater influence.

Many researchers today believe that human behavior is influenced by both nature and nurture, and that it is often the interaction of the two variables that is even more important.

Examples of the Impact of the Nature and Nurture Debate

Few modern psychologists would take an extreme nature or nurture position. Rather than asking which one controls specific variables, researchers are more likely to wonder about the degree to which each of these forces plays a role. So what exactly are the relative contributions of nature and nurture?

According to the research, the answer is about 50/50. Researchers collected the results of nearly every twin study conducted over the last half-century. Doing this allowed them to determine which factors played a role in determining certain characteristics.

Twin studies examine similarities and differences by looking at twins who are either raised together or raised apart. This allows researchers to determine the impact of genes versus the environment.

Researchers analyzed more than 2,700 twin studies involving a whopping 14.5 million pairs of twins from 39 different countries and discovered that genes and environment share a roughly equal role in determining who we are.

Variations in personality traits and disease were determined to be 49% due to genetics and 51% due to environment.

One important thing to note is that while the research suggests a 50/50 split, the findings did reveal that genes do play a greater role in the risk of certain diseases. Bipolar disorder, for example, was found to be approximately 70% heritable.

Examples of How Nature and Nurture Interact

Today, many experts suggest that we should be more concerned with how nature and nurture interact to determine how we develop. For example, we might be genetically inclined toward a certain trait, but our experiences can determine to what degree that trait is expressed.

Height is a good example of how genes and the environment can interact to make you who you are. Even if you inherit genes for tallness, proper nourishment is important for reaching that height. Kids who come from tall families might not become tall if they do not receive proper nutrition during their childhood.

So while we know that both factors are equally important, the question we are left to ponder is just how much of a role each factor plays in the development of certain characteristics. As the research suggests, some diseases are more strongly linked to genetics than to the environment.

As researchers continue to explore how nature and nurture interact, we will continue to gain a deeper understanding of the factors that contribute to who we are.

Haworth CM, Davis OS, Plomin R. Twins Early Development Study (TEDS): a genetically sensitive investigation of cognitive and behavioral development from childhood to young adulthood .  Twin Res Hum Genet . 2013;16(1):117-125. doi:10.1017/thg.2012.91

Institute of Medicine (US) Forum on Neuroscience and Nervous System Disorders. From Molecules to Minds: Challenges for the 21st Century: Workshop Summary. Washington (DC): National Academies Press (US); 2008. Grand challenge: Nature versus nurture: How does the interplay of biology and experience shape our brains and make us who we are ? https://www.ncbi.nlm.nih.gov/books/NBK50991/

Sravanti L. (2017). Nurture the nature .  Indian journal of psychiatry ,  59 (3), 385. https://doi.org/10.4103/psychiatry.IndianJPsychiatry_341_17

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Perceptions of nature, nurture and behaviour

Mairi levitt.

Department of Politics, Philosophy and Religious Studies, Lancaster University, County South, Lancaster, LA1 4YL UK

Trying to separate out nature and nurture as explanations for behaviour, as in classic genetic studies of twins and families, is now said to be both impossible and unproductive. In practice the nature-nurture model persists as a way of framing discussion on the causes of behaviour in genetic research papers, as well as in the media and lay debate. Social and environmental theories of crime have been dominant in criminology and in public policy while biological theories have been seen as outdated and discredited. Recently, research into genetic variations associated with aggressive and antisocial behaviour has received more attention in the media. This paper explores ideas on the role of nature and nurture in violent and antisocial behaviour through interviews and open-ended questionnaires among lay publics. There was general agreement that everybody’s behaviour is influenced to varying degrees by both genetic and environmental factors but deterministic accounts of causation, except in exceptional circumstances, were rejected. Only an emphasis on nature was seen as dangerous in its consequences, for society and for individuals themselves. Whereas academic researchers approach the debate from their disciplinary perspectives which may or may not engage with practical and policy issues, the key issue for the public was what sort of explanations of behaviour will lead to the best outcomes for all concerned.

Trying to separate out nature and nurture as explanations for behaviour, as in classic genetic studies of twins and families, is now said to be both impossible and unproductive. The nature-nurture debate is declared to be officially redundant by social scientists and scientists, ‘outdated, naive and unhelpful’ (Craddock, 2011 , p.637), ‘a false dichotomy’ (Traynor 2010 , p.196). Geneticists argue that nature and nurture interact to affect behaviour through complex and not yet fully understood ways, but, in practice, the debate continues 1 . Research papers by psychologists and geneticists still use the terms nature and nurture, or genes and environment, to consider their relative influences on, for example, temperament and personality, childhood obesity and toddler sleep patterns (McCrae et al., 2000 ; Anderson et al., 2007 ; Brescianini, 2011 ). These papers separate out and quantify the relative influences of nature/genes and nurture/environment. These papers might be taken to indicate how individuals acquire their personality traits or toddlers acquire their sleep patterns; part is innate or there at birth and part is acquired after birth due to environmental influences. The findings actually refer to technical heritability which is, ‘the proportion of phenotypic variation attributable to genetic differences between individuals’ (Keller, 2010 , p.57). In practice, as Keller illustrates, there is ‘slippage’ between heritability, meaning a trait being biologically transmissible, and technical heritability. This is not simply a mistake made by the media or ‘media hype’ but is, she argues, ‘almost impossible to avoid’ (ibid, p.71).

While researchers are aware of the complexity of gene-environment interaction, the ‘nature and nurture’ model persists as a simple way of framing discussion on the causes of behaviours. It is also a site of struggle between (and within) academic disciplines and, through influence on policy, has consequences for those whose behaviours are investigated. There is general agreement between social scientists and geneticists about the past abuses of genetics but disagreement over whether it will be possible for the new behavioural genetics to avoid discrimination and eugenic practices, and about the likely benefits that society will gain from this research (Parens et al. 2006 , xxi). In a special issue of the American Journal of Sociology ‘Exploring genetics and social structure’, Bearman considers the reasons why sociologists are concerned about genetic effects on behaviour; first they see it as legitimating existing societal arrangements, which assumes that ‘genetic’ is unchangeable. Second, if sociologists draw on genetic research it contaminates the sociological enterprise and, third, whatever claims are made to the contrary, it is a eugenicist project (Bearman, 2008 , vi). As we will see all these concerns were expressed by the publics in this study. Policy makers and publics are interested in explaining problem behaviour in order to change/control it, not in respecting disciplinary boundaries, and will expect the role of genetics to be considered alongside social factors. 2

Social and environmental theories of criminal behaviour have been dominant in criminology, and in public policy (Walsh, 2009 , p.7). Genetic disorders and mental illness have provided explanations for a small minority of offenders with specific conditions. A 2007 survey of American criminologists found that ‘criminologists of all ideological persuasions view alleged biosocial causes of crime (hormonal, genetic, and evolutionary factors and possibly low intelligence) as relatively unimportant’ compared with environmental causes (Cooper et al., 2010 ). Sociology textbooks have typically discussed biological theories of criminality only as discredited (Haralambos and Holborn, 2004 , Giddens, 2009 ). Biosocial theories are seen as attractive to ‘agents of social control’ and to be more likely to lead to abusive treatment of offenders. However, with increasing research and public interest in genetics more attention has been paid to biological aspects of crime and to genetic variations within the normal range. Research has focussed on violent and antisocial behaviours which are criminal or may be seen as a precursor to criminal behaviour, for example, antisocial behaviour in young people. Media reports have headlined ‘warrior genes’, ‘the aggressive gene’ and the ‘get out of jail free gene’, all referring to levels of monoamine oxidase A (MAOA) (Lea and Chambers, 2007 ; Levitt and Pieri, 2009 ) 3 . Think tanks and ethics groups have considered the ethics and practicalities of genetic testing for behavioural traits (Campbell and Ross, 2004 ; Dixon, 2005 Nuffield Council on Bioethics, 2002 ).

An attraction of research into genes and behaviour is the hope that identifying a genetic factor that is correlated with an increased incidence of, say, violent and antisocial behaviour, will point to a way of reducing such behaviour. Fotaki discusses the attraction of biological explanations of inequalities in health based on the assumption that genetic interventions ‘would succeed in addressing the causes of ill health that public health policies cannot.’ (Fotaki, 2011 , p.641). The danger is that biological explanations ‘are once more employed for political purposes to explain away the social roots of health inequalities.’ (ibid). Social scientists, and criminologists, have presented biological/genetic explanations of behaviour as dangerous in terms of their potential effect on the individuals or groups identified as genetically at risk. There are obvious dangers of discrimination against, and the stigmatisation of, already vulnerable groups who would be the first to be tested i.e. ‘problem’ families or minority ethnic groups. Discrimination could affect education, employment and family life. The effect of an individual being told s/he has a risk based on a genetic test has been much discussed in relation to health risks (Claassen et al., 2010 . While such information could be motivating, because it is personalised, it can also induce a fatalistic attitude that discourages the person from taking preventative measures. Claasen et al. conclude that it is important to identify those vulnerable to the fatalistic impact and to tailor health risk information (ibid p.194). Identifying risk for behaviour, rather than for disease, is likely to be more problematic because of the difficulty of finding preventative measures that are within the individuals’ own control.

..using DNA to assess risk, make a diagnosis or tailor treatments, may weaken beliefs in the efficacy of preventive behaviour and reinforce biological ways of reducing risk, resulting in a preference for medication as opposed to behavioural means to control or reduce risk (ibid, xiv).

Claasen et al.’s comment on genetic tests for health conditions could apply equally to parents given a behavioural risk for their young child from a genetic test, perhaps before any problem behaviour was evident. The test result could weaken parents’ belief that they could take action to prevent/reduce the risk of the behaviour developing in their child and pharmaceutical solutions, as posited by Caspi et al. might not be available (Caspi et al., 2002 , xvii). However, it is not necessarily the case that evidence of genetic or biological influence on behaviour leads to more punitive treatment. DeLisi et al. give the example of the use of findings from adolescent brain science in the case of Roper v. Simmons in the US which abolished the death penalty for adolescents. On the basis of the research it was stated that young people under the age of 18 ‘are more vulnerable or susceptible to negative influences and outside pressures including peer pressure’ (DeLisa et al., 2010 , p.25) When evidence on genetic traits associated with criminal behaviour has been allowed by courts, mainly in the US, it has so far more often been accepted as a mitigating rather than an aggravating factor in the offenders’ behaviour (Denno, 2009 , Farahany and Coleman, 2006 ).

Environmental explanations of behaviour can, of course, also be presented as deterministic, claiming a closed future for those experiencing poverty and disadvantage. However, it is biological explanations that have caused more concern not only because of the history of eugenics but also because they may be seen as more fundamental, being there from birth, and as harder to change. The public in surveys are reported to see the greatest role for genetic factors in physical features, a lesser role in health conditions and a smaller role still in human behaviour (Condit, 2010 , p.619).

Public perceptions

The model of nature/genes and nurture/environment is still used in behavioural genetics, as well as in popular culture, and has implications for public policy, including the treatment of offenders who claim that a genetic trait has influenced their criminal behaviour. The aim of this research was to explore ideas on the causes of behaviour, particularly violent and antisocial behaviour and examine how respondents use the nature/nurture model. This qualitative research looks at the ways in which lay publics in different age groups conceptualise the factors and influences that made them who they are and their explanations for the behaviour of other people; especially violent behaviour. It was hypothesised that the increased research and media emphasis on the role of genetic factors in health and behaviour might result in an increasing interest in ‘nature’, biology and genes as explanations for behaviour particularly among the young, but, when explaining their own behaviour people might prefer to see themselves as agents with control over their lives. By exploring explanations of behaviour with respondents from different generations, age differences should be apparent.

The views of 78 respondents from 3 generations were gathered by individual interview and questionnaires, using the same open ended questions and responses to two real-life criminal court case studies where environmental or genetic factors had been used by the defence team. Respondents were drawn from a group of retired people participating in an informal ‘senior learners’ programme at Lancaster University, a group of their mainly younger relatives and, in order to recruit more third generation respondents, a group of first year students taking a criminology module. The senior learners group had a programme of talks and discussions and could attend undergraduate lectures. They had, by definition, shown an interest in current issues in a range of fields. There were no educational or age requirements for the group but all the volunteers were retired from paid work and were aged from around 65 years to over 80 years.. They had had similar careers to those popular with social science students; social work, probation, teaching and administrative positions. The senior learners were asked to pass on questionnaires to younger relatives to investigate age differences in attitudes. The first 13 senior learners who responded were interviewed but as only 15 questionnaires were received from their relatives ethical approval was obtained to distribute the same questionnaire to Lancaster University students taking the criminology first year module. Most students were enrolled on social science degrees, including psychology and sociology, and age 18 or 19. While the sample of senior learners and relatives had only a few more women than men, 78 per cent of the students were female reflecting the gender balance on the module as a whole. This makes it difficult to comment on any gender differences in responses. No claims to generalisability are made for this exploratory study. Responses were coded and entered on SPSS and also analysed thematically using Atlas-ti.

The introduction to the interviews and questionnaire was ‘I am interested in your views and ideas on what makes us the people we are; what makes people behave the way they do? What is the influence of nature and nurture?’ The terms, nature and nurture were not used again until the final question. Although the terms were not defined all respondents readily used them with consistent meanings. They identified ‘nature’ with biology, ‘what you are born with’ and genes or DNA and nurture with all aspects of the environment including parenting, socio-economic conditions, the food you eat, culture and other people. Their understanding of environment was therefore similar to that used by genetic researchers; environment as everything that is external to the individual, although they tended to refer more to the social than the biological environment.

A general warm-up question asked whether, in their own family, there was anything they thought of as a ‘family trait’. Then respondents were asked; ‘Imagine a baby swapped at birth and brought up in a completely different family– which influences do you think would be most important – the influence of the birth parents or the influences of the new family- and why?’ 4 The rest of the interview schedule, and the subsequent questionnaire, consisted of open-ended questions.

Respondents were asked how they would explain different kinds of behaviour if they came across a child who is kind and considerate; a young person who displays antisocial and aggressive behaviour adult and an adult with criminal convictions for violence. This was to tap into any differences in general explanations of good and bad behaviour in young people and adults. A quotation about the child killers in the Bulger case being ‘unreformable’ was used to ascertain whether they saw some types of violent behavior, and the actors concerned, as immutable. In order to see how respondents conceptualized the influences of nature/biology/genes and environment/people/experiences in their own lives, respondents were asked to write down ‘what or who made you what you are today’ and any explanation of their responses. Comments were gathered on the introduction of an environmental factor (childhood neglect) by the defence in a violent attack by two young boys in England, and on a genetic factor (MAOA levels) introduced by the defence in an criminal court in Italy. Respondents were asked how they thought such evidence should be dealt with; whether it should affect the degree of blame and whether it should affect criminal responsibility. The final question asked if it mattered ‘for individuals or society’ whether nature or nurture was seen as most important in explaining problem behaviour. Those interviewed were asked if they had any further comments and there was a space for any additional comments on the questionnaire.

This paper focuses on the ways in which respondents employed nature/genes and nurture/environment in their responses as a whole and what other concepts they drew on when explaining behaviour.

Respondents’ explanations of what makes people behave the way they do are discussed through three themes.

• Nurture is more influential than nature
• Nature and nurture interact
• Emphasising nature (but never nurture) can be dangerous

Theme 1: Nurture is more influential than nature

Whether asked about influences on a baby adopted at birth, on their own lives, on an aggressive child or a violent young person, almost all respondents emphasised nurture. Parents and family were seen as the most important influences for babies and young children, moving to peer group and other relationships and experiences for a young person. The explanation for the violent behaviour of an adult had more to do with the individual and the importance of nurture/environment in explaining behaviour weakened. The quotations below explaining behaviour in a child adopted at birth, a young person and an adult illustrate the widening of influences from infancy through childhood and the onus on adults to take responsibility for themselves.

[a child] The environment in which a child grows up in, particularly the influence and role of the parents shapes how a child will grow up and what sort of adult they will be (77 Student). [a young person] I believe that upbringing shapes a person’s personality. Provisions of education, lifestyle opportunities and friendship groups all determine ….outlook. You can see evidence in young people at the school I teach at (20 Relative). Once adult they have to take responsibility for themselves and address whatever has been in their background. An adult can’t turn round and say it’s not my fault (5 Senior Learner).

Participants also saw themselves as shaped by the people surrounding them, starting with their parents, or those who brought them up. Several mentioned the illness and/or death of a parent during their childhood and older respondents talked about separation due to the second world war. Students were especially likely to mention the influence of morals instilled in them by their parents, the core values and discipline that they were taught at home. Educational experiences were important to all. For the senior learners the school leaving age had been age 15, so whether or not they stayed on at school and took public examinations was crucial for their future, and, this decision depended largely on their parents and environment. For the student respondents who had come to university from school, life so far has been ‘kind of set-out’ (41 Student), in the sense that they had progressed through the education system to gain qualifications for university. For their peer group it was normal still to be in education or training at the age of 18.

The lasting effects of early influences were particularly striking among the senior learners, because they were much further removed in years from their childhood. Many related stories about parental influence and also about teachers who taught them at least 50 years ago and had affected them for better or worse. For example a senior learner recalled one of her teachers;

I hated primary school – the teacher in 3rd or 4th year juniors [for ages 9–11] I hated her she was not a nice woman….. I passed to go to the grammar school and it shocked her. She made a derogatory comment – may not have been directed at me but felt it was- about some who should have passed and didn’t and some passing who should not have done…… I always vowed I would never be like that when I was teaching….(11 Senior Learner).

Those who related negative influences presented themselves as active in response, not necessarily at the time but later in their lives. For example a student whose mother had died wrote that ‘it made me more independent’ and another student who was bullied at school wrote that ‘it made me stronger’. The adult had to deal with all the influences (negative or positive) and take control.

Theme 2: Nature and nurture interact

While respondents’ view of themselves and of a child adopted at birth assigned greater influence to environment this did not mean that they held a simplistic model of, for example 60:40 nurture to nature. In this one question when they were asked to choose one or other as the major influence, almost all chose nurture, as many social scientists might do. However, in open questions and comments more complex interactive models were expressed. Environment/nurture can affect genes/nature and vice versa. No one used the term epigenetics but responses referred to the possibility of environmental influences affecting gene expression, for example;

People with certain predispositions (e.g. to violence) are affected by society, and society affects how their genes are expressed (40 Student).

An older respondent reflects on personal experience of child rearing and asks whether nurture is influenced by nature;

I think the nature nurture debate is very interesting. In my family I can see where my children have their own natures that have developed despite being brought up in the same family with the same boundaries etc. However, as a parent did I alter how I nurture them to take into account their nature? (14 Senior Learner).

This quotation illustrates the inseparability of nature and nurture. The child is developing within the family and the parent is developing parenting strategies informed by previous experiences and by other influences including the reactions of the children.

It was obvious to respondents that both genetic and environmental factors impact on everyone (although the role of genes is not yet understood) and it will be harder for some than for others to behave well because of their genes and environment. These people may need different treatment or extra help if they have committed violent and aggressive crimes but that does not excuse their behaviour. Only in exceptional cases, like insanity, can a young person or adult be said to have no choice but to act in a particular way. It is important that people are seen as responsible while also giving them the help they need. In these two comments the treatment for environmental problems and ‘biology’ are similar; the individual can be helped to modify his/her behaviour.

No, [nature and nurture] both play a part, but they can’t be the explanation for everything. Some people grow up in broken homes and get treated appallingly- yet they seem to understand right + wrong and accept responsibility for their actions. There are too many excuses and we never solve any problems, just make them harder to resolve.......I think if you are sane and you know right from wrong you need to suffer the consequences if you’ve committed a crime, but I do appreciate you may need help psychologically if you have anger issues, for example. If we constantly find reasons to diminish blame from people who have committed heinous acts of crime more people will think they can get away with it and it will cause more harm than good (78 Student). Some say you can’t fight your biology, but there are social factors that can stop bad behaviour like learned restraint (72 Student).

The desire to leave a space for individual agency may be linked to the finding that emphasising nature, but never nurture, could be dangerous. It is clear that as children grow up they can exercise more control over their environment, although some have more control and choices than others. On the other hand, whatever the individual is born with (genes and nature) is, or seems to be, less malleable which could lead to different criminal justice policies and different social perceptions of the criminal.

Theme 3: Emphasising nature (but never nurture) can be dangerous for society as a whole as well as for the criminal and victims

The question asked was whether it mattered ‘for individuals or society’ if either nature or nurture was seen as most important in explaining problem behavior. The two most popular answers were that both nature and nurture were needed to explain behaviour, or, that nurture was more important and that there were dangers in emphasising nature. No one in the sample regarded an emphasis on nurture as dangerous or detrimental to the individual or society. On the contrary, emphasising nurture was thought more likely to lead to non-punitive treatment of offenders. There would be attempts to alter future behaviour through improved education and parenting and spreading of knowledge in society about the impact nurture has on young people. Society as a whole would share the blame rather than the individual. As a student put it; ‘society as a whole [would be] open for criticism’ (55 S). An emphasis on nurture was therefore seen as more likely to lead to understanding of problem behaviours and effective treatment, however, the individuals were still to be held responsible for their behaviour.

In contrast there was a mistrust of nature/genetic explanations that again centred on the practical consequences for individuals. It would affect the way criminals were treated by others but could also change their view of themselves. Behaviour would be seen as unchangeable, out of the control of the individual or social action. As a consequence, individual accountability might be removed. The idea that individuals must normally be held responsible for their actions was constantly emphasised (Levitt, 2013 ).

It does [matter] because [if nurture is emphasised] people will care, parent and look after and raise people with more care. However if it’s proven it is nature, then people may lose the will to live (60 Student).

Several SLs referred to the examination at the end of primary education (the ‘eleven plus’) when explaining why they emphasised environment/nurture rather than nature, or, in this case, innate intelligence. The ‘eleven plus’ examination was used to decide which children would be offered a place at an academically selective grammar school and was based on the idea that intelligence, and future academic achievement, could be accurately measured and predicted at the age of 10 or 11.

‘The 11+ was a nature thing. I did the 11+ − it had an effect. Saying children not going to improve or change. Very embedded in the whole idea of nature – it can’t really be true’ (8 Senior Learner).

An emphasis on nature has practical detrimental consequences for individuals. Their status is fixed, for example as ‘not academic’ or ‘born evil’ and suggests, to them and to others, that their ‘nature’ is unchangeable or very difficult to change by individual or social action.

Yes, [it matters] hugely as position of blame is dependent on whether a person chose to do what they did .....nature suggests no control (35 Student).

Those who thought an emphasis on nature meant people were irredeemable either gave that as a reason not to emphasise nature or to suggest that in fact ‘defects’ of nature could be overcome, as in this comment by a student emphasising the power of education;

Yes it is very important because it helps to understand if people are reformable (nurture) or irredeemable (nature). I believe we are determined by our education and thus with the proper help we can change. In the case of people with major biological defects, education is still a way to get over these obstacles and society should be ready to help these people (38 Student).

It might be thought that offenders themselves would embrace a genetic explanation of their behaviour if this was interpreted, as the respondents feared, as meaning they were not responsible for their crimes. However, a small study of juvenile offenders in the Netherlands found that they gave social explanations of their crimes and most rejected the idea that biology might be a factor. They committed a crime for a specific purpose like to get money or to impress others or they gave environmental reasons such as a deprived background or peer pressure or explained their offences were due to psychological conditions brought on by the use of alcohol and soft drugs (Horstkötter et al., 2012 , p.291). Whether they gave goal directed or environmental reasons ‘most of them also state that they had a choice and that it was their choice to commit the crime’ (ibid p.292). As one young offender said in interview;

In the end the person makes the choice himself… The choices I have made also had a share in my past. But in the end I am the one who has made these choices (ibid).

Genes and environment

Respondents were at ease with the language of nature and nurture which was only used in the introduction to the questionnaire or interview. They readily equated genes with nature and nurture with all sorts of environmental influences. There was an acknowledgement that our understanding of environmental factors is greater than our understanding of genetics but that that would change. Older respondents were more likely to be concerned about such a change.

They're going to be doing a lot more with genetics. Influences policy profoundly and people have to be very careful. It worries me that seen to be [more determining]. The complexities don’t get looked at. If you emphasise environment it is safer from a policy point of view because given that most people don’t know what they are talking about it is safer to see the person as redeemable than to come down on the side of genetics and write people off (3 Senior Learner).

This quotation is typical in its view that nature/genes are seen as determining even though the influences on behaviour are, in reality, complex. Like the studies quoted at the beginning of the article respondents often acknowledged the complexities as nature and nurture interact but separated them when explaining the causes of specific behaviours. Students were less likely to be fearful of genetic explanations of behaviour despite their academic interest in social science. However, the hypothesis that young people might be more likely to be interested in genetic explanations for behaviour was not shown in this small study. The senior learners were more likely to refer to reading on genes and display knowledge of genetics. Older respondents and their relatives more often echoed the sociologists’ concerns about behavioural genetics discussed by Bearman earlier (Bearman, 2008 ). For those who feared the practical consequences of genetic explanations, like the respondent quoted above, ‘it is safer’ to keep away from them.

Some respondents in all age groups were prepared for advances in genetics to change their understanding of behaviour and prepared for current views of genes/nature as more basic, fixed and unchanging to change too. One of the youngest relatives, in her 20s, emphasised our incomplete knowledge of genetic influences on behaviour as a reason for focussing on nurture ‘at present’;

It is very tricky as we cannot see genes and I am not sure that I totally trust the idea of blaming genes for violent behaviour- maybe the person has a gene for passive behaviour as well. …….In any case we can change nurture but at present we cannot change nature so let’s do one thing at a time (20 Relative).

As respondents in this small study grappled with explanations for their own and others’ behaviour they focussed on the practical consequences leading to a greater concern over explanations based on nature than the more familiar ones based on a complex web of environmental factors. Whereas academic researchers approach the debate from their disciplinary perspectives which may or may not engage with practical and policy issues, the key issue for the public was what sort of explanations of behaviour will lead to the best outcomes for all concerned.

1 Behavioural epigenetic research has indicated that life experiences can affect gene expression. While controversial the research suggests the possibility of further complications for the nature-nurture relationship as nurture may be said to shape nature (Buchen, 2010 Powledge, 2011 ). 2 Bearman op cit iv. The ESRC Cambridge Network Social Contexts of Pathways into Crime (SCoPiC) promoted multidisciplinary research into the causes of crime and included the E risk longitudinal twin study led by Terri Moffitt which investigated how genetic and environmental factors shape children's disruptive behaviour http://www.scopic.ac.uk Accessed 3 Sep 2013. 3 Violent and antisocial behaviour in this longitudinal study was correlated with a common genetic trait (low expression of MAOA) only where the person was severely maltreated in childhood. Behaviour was measured on 4 outcomes; diagnoses of conduct disorder, psychological tests of aggression and anti-social personality disorder and convictions for violent crime. Caspi et al. 2002 (supplementary material). 4 This initial warm-up question implied that the influences of nature and nurture could be separated and quantified as in common usage both in academic and popular discourses. As discussed respondents were able to express their views more fully (and with more complexity) in the subsequent open questions.

Acknowledgement

The support of the Economic and Social Research Council (ESRC) is gratefully acknowledged. This work was part of the Research Programme of the ESRC Genomics Network at Cesagen (ESRC Centre for Economic and Social Aspects of Genomics).

Competing interests

The author declares that she has no competing interests.

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Nature vs. Nurture Essay

Nature is the influence of genetics or hereditary factors in determining the individual’s behavior. In other words, it is how natural factors shape the behavior or personality of an individual. In most cases, nature determines the physical characteristics which in effect influence the behavior of an individual. Physical characteristics such as physical appearance, type of voice and sex which are determined by hereditary factors influences the way people behave.

Nurture on the other is the upbringing of an individual according to the environmental conditions. That is, the way individuals are socialized. Basically, nurture is the influence of environmental factors on an individual’s behavior.

According to this paradigm, an individual’s behavior can be conditioned depending on the way one would like it to be. Often, individuals’ behaviors are conditioned by the socio-cultural environmental factors. It is because of socio-cultural environmental conditions that the differences in the behavior of individuals occur.

Nature determines individual traits that are hereditary. In other words, human characteristics are determined by genetic predispositions which are largely natural. Hereditary traits are normally being passed from the parents to the offspring. They include characteristics that determine sex and physical make up. According to natural behaviorists, it is the genes that will determine the physical trait an individual will have. These are encoded on the individuals DNA.

Therefore, behavioral traits such as sexual orientation, aggression, personality and intelligence are also encoded in the DNA. However, scientists believe that these characteristics are evolutionary. That is, they change over time depending on the physical environment adaptability. Evolutionary scientists argue that changes in genes are as a result of mutations which are caused by environmental factors. Thus, natural environment determines individual characteristics which are genetically encoded in the DNA.

Conversely, individuals possess traits that are not naturally determined. These are characteristics that are learnt rather than being born with. These are traits which largely determined by the socio-cultural environmental factors or the way the individuals are socialized within the society depending on the societal values.

These traits are learnt as an individual develops and can easily be changed by the socio-cultural environment where the individual is currently staying. These characteristics include temperament, ability to master a language and sense of humor. Behavioral theorists believe that these traits can be conditioned and altered much like the way animal behavior can be conditioned.

From the discussion it can be deduced that individuals’ traits are determined by hereditary genes and at the same time can be natured. There are those traits that cannot be changed in an individual no matter what condition the person is exposed to. These traits are inborn and embed within the individual hereditary factors.

In most cases, they constitute the physical characteristics of an individual. They also determine the physical behaviors such as walking style, physical appearance and eating habits. At the same time there are learned characteristics which are normally being conditioned by the socio-cultural values. Individuals learn these traits from the way they are socialized within the immediate social or cultural environment. In other words, such behaviors are conditioned by the cultural values encouraged by the immediate society.

In conclusion, nature vs. nurture debate still remains controversial. However, all agree that nature and nurture play a crucial role in determining an individual’s behavior. Nature is associated with heredity roles in determining the individuals characteristics where as nurture is associated with the role of socio-cultural environment in determining the individuals behavior.

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• Published: 08 May 2024

Cortical plasticity

Unravelling nature and nurture in cortical (re)organization

• Tina T. Liu   ORCID: orcid.org/0000-0003-0316-5356 1 , 2  

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The extent to which our genetic makeup (nature) versus life experiences (nurture) shapes cortical organization is a perennial question in neuroscience. Although both factors are involved during normal cortical development, decades of experimental investigations have explored their relative effect on the functional specification of different cortical areas. Among these areas, sensory cortical areas were traditionally believed to be hardwired to process specific sensory inputs. However, a groundbreaking study published in 1988 by Mriganka Sur and colleagues questioned this assumption by asking what is intrinsically ‘visual’ about the visual thalamus and cortex — put differently, whether the visual cortex is visual because of the cortical tissue’s properties or because of the sensory inputs it receives.

To answer this question, in newborn ferrets, Sur et al. redirected retinal inputs into the auditory cortex via two main surgical procedures. First, they removed the normal retinal targets by ablating both the superior colliculus and visual cortex, which caused the visual thalamus to degenerate. Second, they created an alternative target space for retinal afferents by sectioning ascending projections from the inferior colliculus to the auditory thalamus, which allowed retinal axons to innervate the auditory thalamus. Through this approach, they showed that the primary auditory cortex could be experimentally induced to process visual information, which highlighted the critical role of sensory input in shaping sensory cortical maps and challenged the notion that sensory map formation is solely an innately specified property of the cortex.

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Sur, M., Garraghty, P. E. & Roe, A. W. Experimentally induced visual projections into auditory thalamus and cortex. Science 242 , 1437–1441 (1988)

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Roe, A. W., Pallas, S. L., Hahm, J. O. & Sur, M. A map of visual space induced in primary auditory cortex. Science 250 , 818–820 (1990)

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Home · Article · Book Review: ‘Christian Nurture’ by Horace Bushnell

Book Review: ‘Christian Nurture’ by Horace Bushnell

Part of bushnell’s thesis is that parents are responsible for the spiritual development of their children; he argues that christian nurture begins in the home..

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Christian Nurture. By Horace Bushnell. Reprint, Memphis, TN: General Books LLC, 2009, 182 pp., $26.71.

“And this is the very idea of Christian education, that it begins with nurture or cultivation” (12).  “Multitudes of parents who assume the Christian name, have yet the practical sense of the intensely religious character of the house, or the domestic and family state” (150). “They want their children to shine, or be honorable, or rich, or brave, or fashionable” (151). These statements were published in 1847, yet seem quite relevant for many Christian families today.

Part of Bushnell’s thesis is that parents are responsible for the spiritual development of their children; he argues that Christian nurture begins in the home. Thus far, contemporary evangelicals would agree. Bushnell’s rationale for his argument, however, is problematic. Despite attending Yale Divinity School at the same time as Nathaniel W. Taylor, Bushnell was a leading proponent of liberal theology and denounced not only the older New England Calvinism but also Taylor’s New Haven theology.

According to Bushnell, children are born with God’s grace and primarily need Christian nurture to live as Christians. Hence, he emphasizes the power of a godly home and godly parents (55). The “organic power of character in the parent” awakens the child’s realization of the Spirit of God (13). Throughout the book, Bushnell bases the power of parents’ influence on his “organic” view of the family. Differing with the individualism of the modern philosophy in his time, he views children as having an organic connection with their parents (18).

In many ways, Bushnell’s exhortation to parents seems refreshingly applicable to Christian parents today. Bushnell’s work, however, misleads parents to believe that faithful Christian parenting somehow ensures faithful Christian children. God commands parents to be faithful nurturers and uses them in the lives of children, but he alone saves. Faithful parents should be honored but God receives the glory in salvation. Bushnell’s theological leanings blind him to the need for personal conversion-from his perspective, a child’s Christian faith needs merely to be nourished and nurtured, not animated and recreated like a corpse being brought from death to life.

In the second half of the book, Bushnell devotes more sections to practical matters of Christian nurture. Section 15, for example, is full of helpful parenting tips (e.g., parents as spiritual examples; husbands and wives honoring each other; children obeying at an early age). Still, the book as a whole will be a ponderous read for contemporary persons. While heartily agreeing with Bushnell’s emphasis on the role of parents, it is crucial to recognize how his theological liberalism moves his foundations far afield.

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The Constant Work to Keep a Family Connected Has a Name

“Kinkeeping” plays a crucial role in a family’s health and well-being, and it’s still predominantly done by women.

By Danielle Friedman

Every December when Erienne Fawcett was growing up, her rural Minnesota home transformed into a showcase of snowy miniature villages, complete with tiny reindeer and carolers.

As a child, the intricate scenes felt like “pure magic.”

It wasn’t until she was an adult that she realized her experience was the result of “hours and hours and hours of work” by her mother — all part of an elaborate effort to make Christmas special.

Eventually, Ms. Fawcett became a women and gender studies teacher at North Dakota State University, where she taught her students that this form of invisible labor, dedicated to family bonding and magic-making, has a name: kinkeeping.

References to kinkeepers began cropping up in sociology literature in the mid-20th century. Researchers defined the role as a family communicator who helped the extended group stay in touch by sharing family news and planning gatherings.

In recent decades, sociology and psychology researchers have expanded the definition to include things like creating or carrying on family traditions, buying gifts for birthdays and holidays, coordinating medical care and performing all sorts of emotional caregiving.

A kinkeeper is someone who cultivates a sense of “family solidarity or connectedness,” said Carolyn Rosenthal, a professor emeritus of sociology at McMaster University in Canada who researched kinkeeping in the 1980s. It’s someone who, in many ways, is the family glue.

One thing that has remained consistent through the years is that most kinkeepers are women: When researchers sought out kinkeepers for a 2017 study , more than 91 percent of the volunteers were women.

Dawn O. Braithwaite, a professor emeritus of communication studies at the University of Nebraska-Lincoln who coauthored the 2017 study and a related one in 1996 , was struck by how little the gender breakdown had changed over the years.

“I thought that maybe men would have kind of picked this up more because of the technological piece,” given the ease with which we can now communicate via text and social media, she said.

Eve Rodsky, a writer, researcher and activist for fair division of labor at home, believes kinkeeping is still mostly done by women because “We still have a huge time disparity in how women and men use their time.” When women set boundaries on their caregiving time, she added, they can experience guilt and shame.

In 2022, one of Ms. Fawcett’s students, Molly Westcott, a college sophomore, created a TikTok video about kinkeeping that quickly racked up millions of views.

In the video, Ms. Westcott lays out an analogy comparing family life to a play: Men are the actors, and women are the production crew, the ushers and everyone else working offstage.

“There’s a lot of effort and time and energy that goes into a play,” she says in the video. “But at the end of the day, when the play is done, people are not clapping for everything that they did not see.”

The observation struck a chord. “It was really exciting that more people got the vocabulary to describe how they were feeling,” Ms. Westcott, now 20, said in an interview with The New York Times.

Ms. Westcott’s video propelled the term “kinkeeping” into the vernacular, inspiring tens of thousands of comments and responses along with podcast episodes and, last month, recognition as Dictionary.com’s “ Word of the Day .”

In many cases, being a kinkeeper is rewarding. “When it’s done from a place of generosity and agency, it can be really empowering,” said Dr. Pooja Lakshmin, a psychiatrist in Austin and the author of “Real Self-Care.” Many kinkeepers genuinely appreciate being the person relatives turn to for emotional support and guidance, or the person responsible for carrying the torch from elder generations.

Kinkeeping fosters a family’s sense of connectedness, identity and well-being, Dr. Rosenthal said. Research also suggests that feeling close and connected to family members supports mental health.

Kinkeepers can also play a crucial role in promoting overall family health, said Caitlin Allen, a social and behavioral scientist at the Medical University of South Carolina who has studied the phenomenon . Kinkeepers even have the potential to save lives by sharing family medical histories and encouraging loved ones to seek out preventative care, she said.

But kinkeeping can be time-consuming — and emotionally heavy.

“When it’s done from a place of resentment or obligation, that’s when you get into trouble,” Dr. Lakshmin said. “Like, is it a real choice?” When kinkeeping feels more like a chore, your mental health — and relationships with family — can start to suffer.

Dr. Braithwaite added that kinkeepers often find themselves “stuck in the middle” of complicated family dynamics or playing the role of “gatekeepers” of important family information — which can come with power, but also stress.

If you are your family’s kinkeeper, a few strategies can help to prevent emotional burnout, the experts said.

A common point of tension is when one family member thinks another is taking on unnecessary work, Ms. Rodsky said. Do the cupcakes really need to be homemade?

Often, however, cupcakes aren’t really about cupcakes — they represent a custom from your childhood that you want to pass on, or they stand for something you didn’t have growing up and want to give your own children. Even seemingly banal tasks can be rich with emotional significance, Ms. Rodsky said.

If you’re not getting the support you need, start by explaining to family members why you do things the way you do. “If we can just step back and spend five minutes on our why ,” she said, “it literally changes everything.”

It’s also important to give yourself grace, said Randi Owsley, a psychotherapist in Boise, Idaho, who co-hosts the Women’s Mental Health podcast and dedicated a series of episodes to kinkeeping. “Self-compassion has a direct impact on reducing stress level,” she said, adding that “in the act of caring for others, we must not forget to care for ourselves.”

If your partner or another member of your family is the kinkeeper, be mindful that this can be “thankless work,” Dr. Braithwaite said.

Simply expressing gratitude for that care — and acknowledging how much work it involves — can help prevent kinkeeper burnout.

And by all means, offer to help: Not only will it take some of the load off a loved one, Ms. Rodsky said, but you will probably benefit, too. Kinkeeping can be a powerful way to nurture your own relationships, and research suggests that relationship quality has an enormous impact on health, happiness and longevity.

“Think about what’s at stake,” she said. “The quality of your relationships is built in these small moments.”

Danielle Friedman is a journalist in New York and the author of “Let’s Get Physical: How Women Discovered Exercise and Reshaped the World.” More about Danielle Friedman

Putin and Xi pledge to ‘nurture’ deepening alliance against United States and the West

V ladimir Putin and Xi Jinping jointly condemned the United States on Thursday as they announced even closer strategic ties and reaffirmed their “no limits” partnership in defiance of Western pressure.

In a clear snub to Washington, whose top diplomat flew to China last month urging Beijing to scale back its relationship with Moscow, Xi said the two leaders see eye to eye on defence and military cooperation, including the war in Ukraine.

“The China-Russia relationship today is hard-earned, and the two sides need to cherish and nurture it,” Xi told Putin as the leaders met in Beijing.

“China is willing to ... jointly achieve the development and rejuvenation of our respective countries, and work together to uphold fairness and justice in the world.”

A joint statement spoke of concerns about what were described as US efforts to violate the strategic nuclear balance, about global US missile defence that threatens Russia and China and about US plans for high-precision non-nuclear weapons.

“Together we are defending the principles of justice and a democratic world order reflecting multipolar realities and based on international law,” Putin told Xi.

Putin’s visit comes three weeks after US secretary of state Antony Blinken flew to China to raise concerns about its support for Russia’s war in Ukraine and a day after he said Washington would continue to impose sanctions on Chinese firms supplying Russia’s military.

The trip appears to have been an unsuccessful attempt to undermine the “no limits” partnership proclaimed when Putin visited Beijing in February 2022, days before he invaded Ukraine.

China claims to take a neutral position in the conflict but it has backed Moscow’s contentions that Russia was provoked into attacking Ukraine by the West, and continues to supply Russia with key components that Moscow needs for its weapons production.

The statement following Putin and Xi’s meeting said that both sides believe that for “a sustainable settlement of the Ukrainian crisis it is necessary to eliminate its root causes”.

China proposed a broadly worded peace plan in 2023, calling for a ceasefire and for direct talks between Moscow and Kyiv. But the plan was rejected by both Ukraine and the West because it failed to call for Russia to leave occupied parts of Ukraine.

Putin’s largely symbolic visit stressed the partnership between two countries who both face challenges in their relationship with the US and Europe.

“Both sides want to show that despite what is happening globally, despite the pressure that both sides are facing from the US, both sides are not about to turn their backs on each other anytime soon,” said Hoo Tiang Boon, a professor who researches Chinese foreign policy at Singapore’s Nanyang Technological University.

Since 2022, Russia has become increasingly economically dependent on China as Western sanctions cut its access to much of the international trading system. China’s increased trade with Russia, totalling $240bn last year, has helped the country mitigate some of the worst blowback from sanctions.

“I and President Putin agree, we should actively look for convergence points of the interests of both countries, to develop each other’s advantages, and deepen integration of interests, realising each other’s achievements,” Xi said.

Xi also congratulated Putin on his election to a fifth term in office and celebrated the 75th anniversary of diplomatic relations forged between the former Soviet Union and the People’s Republic of China, which was established following a civil war in 1949. Putin faced no credible opposition in the presidential race and, like Xi, has not laid out any plans for a potential successor.

AP and Reuters contributed to this report

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Hicks: Student protests nurture antisemitic campus climate

The anti-Israel protests on campuses revealed some of the good, bad and ugly of our universities. Behind them lies hints of Critical Theory, which has captured so many campuses, robbing faculty and students of reason and judgment.

The good news is that protests involved fewer than one in every thousand college students. That means, for every protesting student, hundreds of others were studying for final exams, completing term papers or preparing end-of-course presentations.

The depiction of many protesters as over-privileged and under-informed may be fair, but that is not what I see on campus. Most students arrive with a little intellectual humility and a desire to learn and thrive. Harassing fellow students or barricading the campus are not why they came to college.

The bad was also apparent. Many universities were unprepared, if not confused, regarding how to handle protests. Any president who has not rehearsed a plan to ensure free speech while also protecting property should be looking for a different job. Many failed at that simple task and should go. The harder challenge came with antisemitic threats, which risk creating environments that violate federal civil rights law and campus policies.

Still, after decades of colleges carefully curating students, staff and faculty for a very narrow set of ideologies, many schools seemed shocked to discover there is more than one point of view. This has left some of them helpless and hapless in their response.

There was also more than a little hypocrisy on display. Many faculty members criticized last-minute policy changes or were angered by the police presence, or the techniques they used to disperse students. Those complaints are fair. Still, try to imagine the level of faculty outrage if campus officials summoned armed police to disperse a crowd of students chanting “they will not replace us” or some other noxious white supremacist mantra. There would be none.

To be fair, the protestors and counter-protestors came in many forms. Those outside my office were neither disruptive nor plainly antisemitic. The Middle East has many deep issues that would benefit from honest discussion, and there are there are fair critiques of all sides. There is also more than sufficient suffering to make us care and sympathize with victims.

However, in many places, a deep ugliness descended on American campuses that we must confront. The overall climate of these protests was antisemitic and, frankly, pro-terrorist. I cannot write about this without disclosing my own experience in Middle East wars and in peacekeeping missions designed to prevent another Arab-Israeli conflict.

As a young officer, I was in the midst of some of the most horrific violence the region has seen, including vast refugee columns, devastated cities and murdered civilians. My experiences yield both context and nightmares.

From Chabahar west to Casablanca, from the Mediterranean through the southern Sahara, the neighborhood is a wreck. In that region of 26 nations, there is one functioning democracy — Israel. The rest range from failed states, such as Sudan, to medieval monarchies, such as Saudi Arabia, to full-scale civil wars, such as Syria or Yemen. Ethnic cleansing is common across the region. Indeed, there’s only one nation where religious minorities are increasing — Israel.

Many Middle Eastern nations are full of courageous citizens and struggling governments that wish to craft democracy from the ruins of despotism, imperialism and terror movements. Since the Arab Spring, pro-democracy volunteers continue to fight and die in desperate civil wars in Niger, Libya, Sudan, Yemen, Iraq and especially Syria. They fight radical terrorists, armed groups of thugs and Cold War despots.

A reasonable person might suppose American students would vigorously support that one liberal, multicultural democracy in the region. Or, perhaps, there would be student rallies to support those pro-democracy movements. After all, no human being in the world basks more fully in the blessings of liberty and democracy than a progressive college student.

One might suppose that students would devote themselves to protesting the region’s despots, who operate military dictatorships or 12th-century monarchies. These would surely be targets of an informed, progressive movement.

Most especially, we should expect student protestors to rally forcefully against the radical terrorists. After all, these movements don’t wish women to suffer the inconvenience of education, voting or choosing their husband. The LBGT+ community, which is so active on campus, is largely silent in radical terrorist circles, because they have been murdered.

None of this has happened. The protests on American campuses targeted the sole liberal, multicultural democracy in the Middle East. There is something else at work, an ancient and noxious hatred that has no place on campus. It is antisemitism. We must accept that’s what it is and stand against it.

The claims of Israeli genocide are preposterous. If you believe Hamas’ fabricated numbers, fewer than 1 percent of Palestinians have died in this war. The Syrian Civil War has killed over 15 times the number, without any campus protests.

The protestors would have you believe that Israel has both a powerful and criminal military but lacks the competence to conduct a proper ethnic cleansing. The claims of genocide and ethnic cleansing are just a modern antisemitic trope, without facts or merit.

Many protestors waved the flags of Hamas and Hezbollah, two groups that won popular elections in Gaza and the West Bank. Both explicitly call for the elimination of Israel. It is time to state clearly that waving a Hamas or Hezbollah flag is functionally identical to waving a Nazi flag. We should treat them all with scorn.

The pro-Hamas, anti-Israel protests are funded, directed and promoted by groups with a deep hatred of our liberal democratic values. I doubt most students know this, but faculty and staff participants are well aware.

Hatred of Israel is taught on campuses under the umbrella of Critical Theory. In this view, Israel is depicted as an oppressor and Jews who support Israel are depicted as the epitome of privileged Zionists. This view justifies Hamas and the Oct. 7 murders that precipitated this war.

It is impossible to understand the current explosion of antisemitic protests without appealing to Critical Theory and its anti-liberal focus on race, religion and oppressor status. It is well past time university presidents end Critical Theory-based programming and policies on campus. If not, legislators should do so to prevent these antisemitic protests from becoming more ugly.

Michael J. Hicks is the director of the Center for Business and Economic Research and the George and Frances Ball distinguished professor of economics in the Miller College of Business at Ball State University.