Nature vs Nurture: Definition, Examples, & Debate

By Charlie Huntington, M.A., Ph.D. Candidate​
​Reviewed by Tchiki Davis, M.A., Ph.D.
Science has shown that the nature vs. nurture debate is wrong – it’s really nature and nurture. How do we know this, and what does it mean? Let’s look at some examples and dive into the debate.
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Mental illness runs in my family, on both sides, from my own life to generations back. As a psychologist and a therapist, I have often thought about how this intergenerational transmission of mental illness has unfolded, for no two generations look the same. It is not as simple as saying, “They are a family with depression,” although there is depression on both sides. Instead, in each generation we develop and try to overcome our own personal versions of mental health challenges.
The unique constellation of mental strengths and weaknesses that I possess – this is the result of who conceived me and who raised me. Scientific research confirms what I can see in my own family history and my own life: both nature and nurture impact who we are. (In fact, they interact with each other to determine outcomes.) So why have you probably heard of this debate regarding nature versus nurture? Let’s look at the definition and history of this debate and review some examples to see why we might think things are simpler than they actually are.
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What Is Nature vs Nurture? (A Definition)

For many years, scientists and philosophers have debated the relative merits of viewing our development into mature, adult beings as the result of either nature (i.e., the innate characteristics we inherit from our parents’ genes) or nurture (i.e., all the experiences we have as we live) (Gelman, 2000).

Nature
​In this debate, nature is defined as more than just our parents’ genes (Gelman, 2000). We can add to this category any knowledge that seems baked into each species such that it does not need to be learned. For example, many species instinctively stop near the edge of the physical plane that they are on – they recognize without having to learn the hard way that if they kept going, they would fall down that cliff or steep hillside and hurt themselves. The capacity for language also seems to be innate to humans – all of us, as long as we grow up exposed to one, are born capable of learning most any language.
 
Nurture
On the other side of the nature vs. nurture debate are scientists who argue that most of what matters in our lives are things that we learn as we grow. Since much of our learning occurs under the care of older humans, this is the nurture side of the debate. On this side of the debate, scientists are concerned with arguing that there is very little that is innate to our existence and that most anything of importance is learned (Gelman, 2000).
 
I am going to get this out of the way at the start – sorry if it spoils the suspense, although maybe how I described my family history did that anyways: there are almost no examples in the development of humans, or any species, of personality traits or behaviors that are solely the result of nature or nurture (Stiles, 2011). It is almost always a case of nature and nurture interacting to shape who we are. In any given moment, I am the sum total of all my genes, all of my experiences, and all the changes that have happened in me as my genes have impacted my experiences and my experiences have impacted my genes (Stiles, 2011).
 
Scientists have a word for the phenomenon of our genes and environments interacting to shape who we are: epigenetics (Haque et al., 2009). To understand why it is almost always nature and nurture, not nature versus nurture, we will look at many examples of epigenetics in action in this article.
 
For some helpful visual depictions of how epigenetics works, I recommend watching the following brief video:

Video: Nature vs Nurture | Genetics | Biology 

Examples of Nature vs Nurture

Let’s look at a simple example. Morehouse and colleagues (2016) studied conflict behaviors in bears living in the wild. Importantly, they looked at bears who were not being raised by their biological parents. Why would they do this? They wanted to isolate the impacts of genes and environments – if you are raised by somebody other than your mother and father, then in theory the only impacts your parents have on you are through the genes they gave you.
 
What Morehouse and colleagues (2016) found was that the offspring of bears that got into a lot of conflict were also more likely to get into conflicts as they grew up. But, the researchers also found that bears raised by mother bears that experienced lots of conflict had more instances of conflict themselves, regardless of how much conflict their biological parents experienced. In other words, both nature and nurture were influencing how much conflict behaviors these young bears engaged in.
 
Once scientists came around to the idea that almost everything is the result of nature and nurture and their interaction, they became very interested in identifying how those interactions take place and when one aspect might be more influential than the other. For example, Matison and colleagues (2022) investigated the heritability of people’s choices in eating different fruits and vegetables. (Heritability means the degree to which something is determined, on average and across an entire species, by their genes.) They found different levels of heritability for different vegetable preferences, whereas people’s genes did not seem to influence their fruit preferences. (My pet theory about these results is that fruits are generally sweet and almost everybody loves them, while the vegetables you eat might be more influenced by what your parents fed you growing up.)

History of Nature vs Nurture

So, who started this nature vs. nurture debate in the first place? While scientists and philosophers have long debated the degree to which we get our characteristics from our parents, it seems that this debate began more formally when a famous behavioral geneticist named Francis Galton proposed that criminal tendencies are simply inherited from one’s parents (Galton, 1874). This provocative statement seems to have set in motion much reflection and research by other scientists.
 
Ironically, Galton also pointed out an opportunity for studying the nature versus nurture debate that would end up providing most of the evidence that it is in fact nature and nurture: he proposed that looking at the lives of twins could help us distinguish between what people receive from their parents versus from their environments (Galton, 1865).

Nature vs nurture in twin studies
Since then, large-scale studies of twins have sought to do just that (Plomin et al., 2003). There are two kinds of twins. Identical twins, or monozygotic twins, share all of their genes, while fraternal twins, or dizygotic twins, share half of their genes. By studying monozygotic twins, in particular those that have been raised in different environments, scientists can attempt to isolate the effects of nature and nurture (Bouchard et al., 1990). In other words, these twin studies can help us see what the impact of our genes is, separate from our environment and epigenetic changes (those changes that result from the interaction of genes and environment).
 
These studies have shown that genes do strongly influence who we become (Bouchard et al., 1990), although the degree of influence varies from trait to trait. Knowing this, scientists can then look at the differences in genes across these twins to try to determine which genes, or groups of genes, most strongly influence these outcomes. And if there is great variation in how certain diseases happen across these twins, we can reasonably guess that the environments they live in are more influential than their genes in shaping that disease risk (Boomsma et al., 2002).
 
At the same time, these twin studies also offer a window into which aspects of our environments influence our development the most. For example, researchers might study the parenting behaviors of identical twins who were raised apart. They study this in order to determine how (and how much) specific parenting behaviors influence our development. These studies can help us see epigenetics in action – if you and I had the exact same genes, but were raised in very different ways, then we could probably point to the different outcomes in our lives and say, “this is a result of how we were raised and how that changed our genes over time” (Haque et al., 2009).

Nature vs Nurture Debate and Controversy

The debate and controversy around nature versus nurture reflects how the science clashes with beliefs in things such as free will and responsibility for our actions (Robinson, 2004). If our genes – or our environments – determine who we are and what we do, do we have free will? And if epigenetics is a powerful force in our lives – if our genes are literally reprogrammed over time by the experiences we have – should we be held responsible for our behaviors?
 
For example, should someone who was raised in poverty and abuse by parents who were naturally aggressive and who grows up to commit a violent crime be held fully responsible for that crime? If growing up wealthy or poor seems to determine our future finances much more than our innate abilities (Black et al., 2020), are we living in a just world?
 
At the same time, should we ignore innate biological differences simply because it is compelling to think about and try to change social environments to create a more equitable world (Eysenck, 1980)? Often, social scientists are accused of doing just this – ignoring established biological differences because it complicates their theories of social change (Singer, 1999).

Is Nature or Nurture More Important?

Scientists are coming to agree that while in rare cases nature or nurture is clearly more important in determining a particular outcome, it is usually their interaction, and the epigenetic changes that result, that is most impactful (Traynor & Singleton, 2010; Wermter et al., 2010). 

Let’s look at an example: a child who inherits risk for anxiety from their parents may grow up in a household where people avoid things that make them anxious. That child learns to worry and avoid, and the genes that predisposed them to be anxious can get expressed more strongly over time (Kendler et al., 2007). For many such diseases and disorders, our genes alone can only tell a small part of the story; the rest is in how those genes change over time with our experiences (Miller & Jones, 2014).

How Does Nature vs Nurture Affect Human Development?

Twin studies offer a window into how much nature, nurture, and their interaction determine aspects of human development. For example, it would appear that on average, a person’s weight is determined mostly by their genes, as is their likelihood of being hyperactive; the environment is less influential in determining these outcomes (Plomin et al., 2003). At the same time, twin studies show that our environments strongly impact our cognitive development, perhaps just as much as our genes (Plomin et al., 2003).

How Does Nature vs Nurture Affect Personality?

According to studies, our personalities are 43% heritable, meaning that on average, we can explain 43% of the differences in people’s personalities by looking at their genes (Plomin et al., 2003). This means that more of the differences across people are determined by our environments and how those environments influence our genes than by the genes themselves.

How Does Nature vs Nurture Affect Mental Illness?

The nature versus nurture debate has led scientists to look closely at how mental illness develops. They have found that certain mental illnesses are more heritable than others, but in general, it is the interaction of genes and environment that most influences our risk of developing mental illnesses (Wermter et al., 2010). These interactions are incredibly complex; attempts to determine how much changes in certain genes are related to changes in risk have shown that it is almost always changes across many, many genes that influence our risk (Uher, 2014).

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Final Thoughts on Nature vs Nurture

I personally take a lot of comfort in knowing how the nature versus nurture debate has played out. The fact that our genes change over time, according to the experiences we have, means that we get to change ourselves. None of our traits and tendencies, whether good or bad, pleasant or unpleasant, are permanent. Insofar as we are ready, willing, and able to change our environments and choose different experiences, we can mold ourselves over time into different people – ideally, the versions of ourselves we have always wanted to see. I am not saying that it is easy, but I hope this article makes clear that the science supports it: we never stop changing and very little about us is fixed in place, so we can take action to determine what those changes look like.

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