The Mental Health Debate of Nature vs. Nurture

Known as one of the biggest debates in the history of science, the conflict between nature versus nurture has led to some significant conversations around the relative contributions of environment and genes. This type of debate has shaped many fields of science including biology, chemistry, and psychology. At its most basic, nature refers to how biology, genes, and hereditary influences shape someone and their behavior. On the other hand, nurture refers to the ways in which environment (e.g., experiences, relationships) can lead to changes in someone and their behavior.

Therefore, nature refers to genetics and biology whereas nurture refers to the influence of environment. Looking into how nature and nurture have affected science, human behavior, and biology has created a lot of discussion across many scientific fields. Specifically, it has led to ample amounts of research into how much genetics and environment play a role in human behavior. Twin studies have been developed and other genetics research to examine these questions. Known as one of the most monumental and earliest forms of debate in the field of science, it has sparked numerous important discussions that continue today.

Within the field of psychology, the nature or nurture debate has shaped views on human behavior, the development of mental illness, and the treatment of mental health disorders. Depending on what branch of psychology you are in, then you will find opposing views on how much both nature and nurture contribute to each of these issues. Overall, most psychologists and researchers agree that nature and nurture play some role in these concerns, although they vary with how much they will impact each. Within this article, you will learn more about the nature versus nurture debate. Specifically, you will learn about how the debate developed from a long time ago, examples of the debate within the field of psychology, and current views on the impact of nature vs. nurture.

What is the Nature vs. Nurture Debate?

The Nature or Nurture debate boils down to a few questions. Does the environment or biology impact your behavior? Which is more important in the development of human behavior? Is it either nature or nurture or do they both impact behavior? This debate is nothing new to the field of psychology or in general to additional sciences. This debate has fostered significant research over the years and has led to great discussions among scholars, researchers, and intellectuals on just how much is related to the development of mental health concerns, biology, and behavior. Within this article, you will learn about how the debate about nature vs. nurture developed, some common examples, and where the field of psychology stands on the debate currently.

How did the Debate Develop?

The history of the debate can be traced back many years. Even from the time of Plato, philosophers have questioned how much of an impact biology and genes have on human behavior. Galen, a Greek philosopher, also argued for the impact of biology on the development of humans. He published his research in a book entitled “English Men of Science: Their Nature and Nurture” which suggested that cognition and personality were the result of genetics and hereditary traits. Similarly, John Locke coined the idea of humans being a tabula rasa or a blank slate, referring to the nurture side of the debate and how humans are ultimately shaped by their experiences.

The phrase nature versus nurture was not coined until much later however. In 1869, Francis Galton coined the term nature versus nurture following his research on twins. Francis Galton studied twins to determine how much nature and nurture relatively impacted behaviors and looks, and ultimately concluded that nature makes the biggest impact. Galton’s research was ultimately the beginning of a lot more of research into twins and how nature and nurture can impact the development of certain behaviors.

In the 20th century, there was a great expansion of interest into the role environment plays in human behavior. Much of this sparked interest can be attributed to Charles Darwin, and his theory of evolution. The interest in environment and nurture sprung about as a reaction against how strong of a role biology plays in the development of human behavior and motivation.

In the 1940s and 1950s, Ashley Montagu, who was a behaviorist which will be discussed in greater detail later, argued that genetics and hereditary influences do not impact the development of human behavior at all. Instead, they argued that environment is the single factor that impacts human behavior.

Even in current day, the nature vs. nurture debate remains with many psychologists and branches of psychology arguing that one is more important than the other. Each area of psychology can find different ways to portray the relative importance of both nature and nurture. Some of it is related to their theoretical views of the relative importance of nature and environment. The nature vs. nurture debate is not inherent to the field of psychology but rather is seen across other fields in which science has sought to understand the importance. However, in the next section, we will touch on how the nature and nurture debate has shaped the field of psychology and the different theoretical views that have emerged.

Nature vs. Nurture Debate in Psychology

Within the field of psychology, the nature versus nurture debate was also often seen as rooted in differences between nativism and empiricism. Nativism places the importance of innate ideas and being born with certain traits and ideas. Empiricism on the other hand originates from the idea that environment shapes how someone develops. Out of these differences in psychology, different branches developed their own views of how much nature and how much nurture ultimately impacts the development of human behavior. Within the next section of this article, we will review how various branches in the field of psychology view the nature vs nurture debate and their current thoughts on the approach to psychology.

Psychoanalysis

Psychoanalysis, popularized by Sigmund Freud, relies heavily on the impact of both nature and nurture and its impact on human behavior and mental health. Freud views everyone as having innate drives that are unconscious and influence our behavior, emotions, and reactions. According to Freud, the id is the unconscious drive that we are all fighting against and that impacts our behavior. On the other hand, the ego and superego we are consciously aware of and they shape our behaviors. Although Freud did not directly state that he believes the id is a reflection of genetics, he asserted that it was innate to everyone. Because of this, his view of the id can be considered a more naturistic approach to the development of humans.

However, psychoanalysis also heavily weighed the impact of nurture and early experiences on the development of human behavior, feelings, etc. Freud believed that people operated according to the reality principle, which is the ability of people to assess the reality of the world and to act upon it. Based upon this principle, people are interacting with the world in a way that ends up shaping their behavior. It is due to their environment that they are acting in a certain way. Seen in this way, the nature vs nurture debate according to Freud is a result of both nature and nurture.

In psychoanalytical therapy, Freud is well-known for also having patients recall their early life experiences. From these early life experiences, he will draw upon how they have affected his patients and use them as signs for their current suffering. Therefore, Freud and his psychoanalytical therapy rely heavily on nurture as a way of explaining human behavior.

Behaviorism

Behaviorism on the other hand operates from a significant viewpoint of nurture having the greatest impact on how someone behaves and what they do. Radical behaviorists, such as John B Watson, believe strongly that the environment in which someone is raised contributes significantly to the way in which their intelligence is shaped, their personalities develop, and how they act on a day to day basis. One of the most famous quotes by John B Watson illustrates just how much he viewed nurture and the environment as impacting the development of humans. John B. Watson stated, "Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select - doctor, lawyer, artist, merchant-chief, and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors." Therefore, Watson clearly believes that the way in which the environment shapes someone is even more important than their genetics and how their biology impacts them. 

Within the field of behaviorism, the impact of early life experiences is also seen as an important factor. Specifically, past learning experiences shape how someone interacts with their environment today. Classic studies of Albert and his fear of white animals show that when someone is conditioned to be afraid of animals in white, these past experiences will shape how afraid they are of other situations. As a result, behaviorism has shown how environment can play a role in the development of mental health disorders and concerns.

Behaviorism has certainly been a significant field within the larger realm of psychology that has suggested how important the environment is in shaping behavior. At the same time, the field of behaviorism has drawn a good amount of criticism by those who believe that it is not the only thing that can shape behavior. Those who are against behaviorism argue that they do not take into account enough the role that genetics play. Interestingly, many behaviorists have argued that the environment is the only thing that contributes to factors such as intelligence and personality as well. Given that behaviorists have a stark and drastic view of the role of environment and nature, other viewpoints are also considered.

Behavioral Neuroscience

The field of behavioral neuroscience developed as a way to utilize biology to explain human behavior. Behavioral neuroscience is often also termed as biological psychology due to its reliance on the importance of behavioral and biological methods to understand human behavior. Claude Bernard, Charles Bell, and William Harvey are often recognized as contributors to the field of behavioral neuroscience. The case of Phineas Gage also led to an exploration of just how important biology is in human behavior and the influence of the brain. 

The field of behavioral neuroscience uses specific research method techniques in a way to understand the influence of genetics and neuroanatomy on behavior. For example, they may form lesions as a way to understand the relative influence of certain brain parts on behavior. Additionally, they may stimulate other brain parts to understand just how much they influence behavior.

The field of behavioral neuroscience has researched a wide variety of topics and examined just how neuroanatomy may affect these areas. Specifically, the topic areas of sleep, circadian rhythms, mental health disorders, appetite, and emotion are all important to the field of behavioral neuroscience. 

Of course, given that behavioral neuroscientists focus exclusively on the development of brain areas and their influence on behavior, they have drawn criticism from behaviorists and others who argue that environment plays a much more central role in behavior. Therefore, behavioral neuroscientists may be seen as more of a nature perspective than a nurture perspective.

Language Development

Within the field of psychology, the idea of how language develops has led to some opposing views on the relative impact of both nature and nurture. Noam Chomsky, was famous for his views on how the impact of biology and nurture impacted the development of language. Chomsky believed that the development and acquisition of language was innate to all humans and all humans were capable of developing language. He developed the idea of a language acquisition device, in which every human has an internal device that influences their ability to have language. Chomsky’s belief in this device suggests that even certain aspects of language are innate to all humans. For example, he believes that we all have a set of grammar and rules that we follow that are innate, rather than that are taught to other humans. Chomsky’s beliefs in the innate nature of language have developed some criticisms of its approach. For example, Chomsky’s beliefs are criticized as not taking into account culture and how that may influence the development of language.

Chomsky’s idea of the innate language acquisition device has drawn heavy criticism from others who believe that language is developed more as a way of nurture, environmental experiences, and education. On the opposing side of Chomsky’s nature approach to language development is Tomasello. Tomasello believed that the development of language depends significantly on how much you use language, and if you don’t use language, then you will end up losing it. Tomasello’s views sit firmly on the nurture perspective where humans and children learn language by watching other adults use it. Through this type of observation, children watch for patterns in the use of language in adults. 

Despite the amount of research that has been conducted on the development of language, we still do not know how adults and children develop language. Likely, the best way to describe the development of language would be a combination of approaches that combines both nature and nurture.

Personality

Personality traits, specifically the Big 5, appear to have some evidence for the impact of genes on their development as well as nature. The Big 5 Personality traits are agreeableness, openness to experiences, conscientiousness, extraversion, and neuroticism. Research has found that personality traits are approximately 50% heritable, suggesting that your parents DNA has a large factor in how your personality itself is developed and shaped. Robert Plomin, a pioneer in the field of genetics, suggests that genetics play a large proportion in the role of personality and other characteristics. Although this leaves approximately 50% of the development up to environment, Plomin argues that it is much more about how these genes are expressed due to the environment rather than the environment itself. Plomin’s view of personality is similar to those who take an interactionist perspective, which is described in detail later.

Intelligence

Intelligence is also an area of psychology in which much research has looked into just how much genetics and environment play a role in its development. Twin studies have found that intelligence is highly heritable, particularly from maternal influences. Therefore, it appears that the role of genetics in determining intelligence is an incredibly important one. On the other hand, there is also research to suggest that how parents interact with their children influences their cognitive abilities. For example, parents who read and speak more to their children are much more likely to have children who develop greater intelligence, suggesting that the environment plays a significant role in the development of intelligence as well. Together, these findings suggest that while nature is very important in the development of intelligence, it is not the only factor that comes into play in the development of intelligence. This will come into play much later as we discuss the interactionist perspective.

Mental Health Disorders

A lot of research has paid attention to how the development of mental health disorders may be related to a combination of both nature and nurture. There is significant evidence that the development of mental health disorders has a strong genetic component. For example, many mental health disorders are more likely to be present if you have a family member who also has been diagnosed with this disorder. Although this may be difficult to tease apart how much is related to genetics and how much is related to observations of behaviors, it appears that genetics does play a significant role in the development of mental health disorders.

For example, in families with Bipolar Disorder, a child is much more likely to be diagnosed with Bipolar disorder as well. The same can be said about other genetically based mental health disorders such as ADHD, OCD, eating disorders, etc.  Although there is a significant amount of research suggesting that genetics and biology do account for a lot of the development of mental health disorders, much research also suggests that it is not the only cause of mental health concerns. Instead, environment can also play a significant role in the development of mental health disorders.

For example, the diathesis-stress model of schizophrenia suggests that the development of schizophrenia is due to a combination of both genetic influences and environmental factors. According to this model, someone may be genetically predisposed to experiencing schizophrenia based on their family history, genetics, or genes that place them at a greater risk of schizophrenia. The stress aspect of the model suggests that there is a stressful life event that then makes it so that these genes are expressed. This is similar to gene environment interactions which are discussed later in this article. Therefore, the development of schizophrenia has been seen as a combination of both genetic factors as well as factors related to the environment.

For individuals with eating disorders, there is evidence that genes account for a significant portion of the development of eating disorders. People with eating disorders tend to have lower levels of certain neurotransmitters, such as serotonin that make it much more likely they will engage in eating disordered behaviors. Then, when someone with an eating disorder is exposed to models of unhealthy eating habits or if they experience social stress, they may further develop an eating disorder. Therefore, the development of eating disorders can be seen as a combination of both genetics and also environment.

The same can be said for anxiety disorders. Anxiety disorders tend to run in families, with an increasing risk of developing an anxiety disorder (e.g., generalized anxiety disorder, social anxiety) if a parent also has the disorder. Anxiety disorders are difficult to tease apart just how much is related to genetics and how much is due to observations or interactions with a parent. For example, parenting behaviors in which parents accommodate their child’s anxiety (e.g., letting a child stay home from school when they are anxious) tends to lead to more anxiety over time. Therefore, this is a way in which anxiety tends to increase as a result of parenting behaviors that are not a result of genetics.

For some neurodevelopmental disorders, such as Attention Deficit Hyperactivity Disorder and Autism Spectrum Disorder, there is strong evidence that they are the result of genetics and differences in the brain. Specifically, Attention Deficit Hyperactivity Disorder has a strong genetic basis where you are much more likely to be diagnosed with this disorder if you also have a sibling or parent who has this disorder. Additionally, there are other genetic influences which may impact the development of Attention Deficit Hyperactivity Disorder. Specifically, having low levels of serotonin in the brain leads to an increased risk of Attention Deficit Hyperactivity Disorder. Additionally, having in utero exposure to drugs, such as cocaine, can make it much more likely to experience ADHD or other mental health concerns. These genetic influences can heavily impact the development of some mental health disorders.

Additionally, disorders such as Huntington’s Disease suggest that almost all of the traits and characteristics associated with it are due to genetics. Someone who is born with a specific gene will be much more likely to express the gene and develop Huntington’s disease. The development of Huntington’s disease is related to a defective gene on chromosome 24. Additionally, since this is a dominant gene, it has a much higher chance of being expressed than a recessive gene. Similar to other mental health concerns, the development of Huntington’s Disease is highly related to mental health concerns.

Some mental health disorders require the experience of an environmental factor in order to develop the mental health disorder based upon the criteria set out in the Diagnostic and Statistical Manual. Specifically, the development of Post Traumatic Stress Disorder, PTSD, requires the experience of an environmental event, a trauma, in order to meet criteria for the diagnosis. This means that although someone may have a genetic predisposition to PTSD, they have to experience life events, environmental factors, etc. in order to meet criteria. This is one case in which there is a clear need for environmental factors or nurture to experience the development of a mental health disorder.

Overall, it appears that a combination of both genetic factors, family history, as well as early life experiences makes it much more likely that you will develop a mental health disorder. It is not one factor that ultimately leads to the development of mental health concerns, but rather the combination of a variety of factors.

Twin Studies

To better understand the relative influence of both genes and environment on the development of human behavior, there was a significant increase in the amount of twin studies that underwent as a way to study these influences. Twins are one of the only ways to truly study how much genes and environment interact together because you may have twins who have the same genetic influence but who are raised in different environments. Because of this unique situations, twin studies in the field of psychology have been very important in understanding just how much genes and environment interact with each other.

Twin studies are often used to study heritability, or just how much someone’s genetics impact their behavior or mental health concerns. Twin studies have established that in many ways, genes are very important to the development of mental health concerns. Estimates of heritability, or just how much genes within your family interact has suggested that they typically account for 40-50% of the chance. With advances in genetics testing and research, heritability studies have become much easier to perform. The heritability index is a statistical quantification of just how much someone’s genetics influence their behavior. Traits with high heritability typically means that there is a significant amount of likelihood someone else will have the trait as well. Eye color and blood type are examples of traits that have high heritability characteristics on this index. Other types of characteristics seem to have more variable heritability indices.

Treatment of Mental Health Disorders

The treatment of mental health disorders also gives evidence into how the impact of environment and genes can impact the development of mental health disorders. Psychopharmacology, or the study of how psychiatric medication can impact mental health disorders lends itself to the nature side of the argument. Specifically, these medications act on neurotransmitters within the brain in an effort to change how they impact human behavior. These neurotransmitters are something innate to someone and cannot be changed based upon their environmental experiences. Therefore, the treatment of mental health disorders through pharmacological treatment can suggest that nature plays a very important role in the treatment of mental health disorders.

In contrast, therapy focuses more on changing the environmental side of mental health disorders. Specifically, therapy often looks at how someone’s environment has shaped their experiences and mental health as they are today. Then the therapist helps guide the person into changing their environment in a way that can be more helpful and reduce the impacts of their mental health on their overall functioning. There is some evidence to suggest that certain types of therapy can reduce the impact of mental health symptoms overall. For example, exposure and response prevention therapy leads to successful treatment of OCD in about 90% of cases of people after a certain number of sessions.

The treatment of mental health disorders lends itself to the suggestion that mental health and behavior is a combination of both nature and nurture. While there is evidence that it can be treated by psychopharmacological approaches, it has also been suggested that environmental factors can make a significant difference in how someone’s mental health is affecting their life. Taking this approach also has evidence behind it given that a combination of both therapy and medication has in some cases been shown to be more effective than either of the approaches alone. This is particular true for the treatment of ADHD, anxiety, and depression.

Gene Environment Interactions

Although much of the debate has focused on how nature and nurture are opposing views on how it can develop human behavior, it’s important to understand how genes and environment interact with each other. In contrast, a gene environment interaction refers to how the environment can lead to some genetic traits being expressed more easily. This contrasts with how genes are not always set in stone and do not fully determine how someone’s behavior will be. The view that genes and environment interact with each other is often described as the interactionist perspective.

There are multiple examples of how genes and environment interplay within the field of psychology that leads to the expression of certain traits rather than others. For example, there is some evidence that autism is a result of the interplay between genetics and environment based on some research. For example, with autism, there is evidence that children with the genetic variant of MET who are exposed to air pollution are more likely to develop autism. Overall, the field of psychology is moving towards an interactionist perspective in which both genes and the environment have significant roles in the 

Additionally, for individuals with Parkinson’s disease, there is some evidence that the development is also a combination of genetics and environment. For people who have a genetic variation linked to Parkinson’s and who also are exposed to pesticides, they are more likely to develop Parkinson’s than those who aren’t exposed to pesticides. These all show how genes and environment can often interact, leading to the development of these concerns.

These gene environment interactions are very difficult to tease apart with research but they help to understand how both nature and nurture can come together to lead to developments of behavior and mental health disorders. This is part of why using twin studies has been so important in understanding the development of mental health concerns and disorders. In addition to twin studies, there have been significant developments in genetics research that have made it easier to understand the relative influence of each part.

Current Thoughts on the Debate

Currently, most experts believe that human behavior is a result of not one or the other but an interaction between nature and nurture. This perspective is often termed as an interactionist view of behavior, in which nurture and biology are important yet so are the environment and ways in which the environment shapes those. Taking this approach has many benefits in that you can understand people through a variety of perspectives rather than just one.

As described within this article, there is mounting evidence for the combination of both genetics and environment in the development of human behavior and mental health disorders. The development of many mental health disorders is not attributed purely to genetics, as in many cases, it is actually the environment that leads to the expression of genes that leads to the development of a mental health disorder. Similarly, the development of cognition, intelligence, and language can be seen as a combination of a variety of factors including genetics and environment.

Within the interactionist viewpoint, it argues that you cannot feasibly separate genetics from the environment because of how intertwined they are. As described in several sections previously on the impact of the development of mental health concerns, it is easy to see just how difficult it is to tease apart each of these areas. Specifically, how can you truly tell if the development of a mental health disorder is due to environmental influences or genetics. In so many cases, parents are responsible not only for the physical and genetic influence of these mental health concerns, but also the environment’s impact on these mental health concerns. Therefore, an interactionist perspective argues that it is incredibly difficult to distinguish between these two viewpoints because they are ultimately intertwined in a way in which they will never been able to be separated out.

Overall, most contemporary researchers, scientists, and psychologists agree with the interactionist perspective. They argue that the nature versus nurture debate is not one of dichotomous views that cannot come together, but instead is one in which they interact together in order to lead to the development of human behavior and mental health concerns. This balanced view takes into account how important both the environment and genetics are in the development of mental health concerns. Because of this balanced view, researchers are better able to account for just how much of an effect each of these areas have and support people experiencing them. The study into the nature versus nurture debate is one that has taken the forefront of science and psychology over many years. It will continue to grow as research topics advance and we are better able to fully understand just how much of an impact genes and environmen can have on human behavior.