Nature Vs. Nurture: Examples to Understand the Relationship

In my clinical practice, I’m asked constantly about the nature vs. nurture debate. In reality, it’s actually more of a nature AND nurture situation. The two work together constantly to create our personalities, experiences, and behaviors

Much research has been done on the subject, with varying findings. Generally, 45-50% of personality traits are believed to be heritable. However, many different aspects of life experience both in childhood and adulthood can influence behavior significantly.

Nature vs Nurture Examples in Psychology

We don’t have data on every single quality or characteristic of humans. We do, however, have some research on several different aspects that can help us understand the relationship between nature and nurture.

Intelligence

When investigating intelligence, research finds that it is anywhere from 40-80% genetic. This means that one’s genes are 40-80% responsible for their intelligence as far as we currently understand. In my opinion there are many problems with measuring intelligence via IQ tests, but that’s a topic for another time. 

The other 20-60% is environmental. We’ll cover this more down below, but common factors that are believed to influence intelligence include high socioeconomic status, high parental education, urban residence, high health scores, strong social interaction, and many more.

It’s also worth noting that research has suggested the environmental factors may be different for individuals with different inherited intelligence. For example, individual with higher IQs show more susceptibility to environmental factors into adolescence. This means their intelligence can be influenced into their teen years.

On the other hand, those with lower inherited IQs tend to see a decline in environmental influences sooner. Their IQ is more stable in pre-teen years and is less influenced as they move into adolescence.

Mental Health

When it comes to mental health, we again see a relationship between nature and nurture rather than one against the other. Studies suggest generalized anxiety disorder (GAD) is believed to have a heritability of around 30%. Research on substance use disorder finds around a 50% heritability rate.

However, just because you have a family member with depression, anxiety, or substance use disorder doesn’t necessarily mean you will as well. Environmental factors play a big role. Adverse childhood experiences, chronic stress or burnout, financial insecurity, and unpredictable routines may increase the risk.

Let’s say you have a parent with generalized anxiety disorder. You are at a higher risk for developing the same disorder at some point in your life. However, your environment is not one that is known to cause anxiety. You have a mellow job, happy family life, and financial security. You may not ever develop any symptoms of an anxiety disorder.

On the other hand, you may have absolutely no family history of anxiety (no “nature” predisposition). But you had difficulties at home as a child, such as financial stress or divorce. As an adult you work in a high-pressure office where you spend ten hours a day. Even though you have no genetic predisposition, the nurture side may still cause an anxiety disorder to develop.

Cancer

I offer this example of nature vs. nurture because it makes the point very clear in my opinion. It’s not directly related to psychology or mental health, but helps illustrate the point. We’re going to look specifically at genes known as the BRCA genes.

Mutations in these genes (BRCA1 and BRCA2) are strongly associated with the development of cancer, especially breast cancer. More than 60% of women who inherit a mutated BRCA gene will develop breast cancer, compared to only 13% of women with typical BRCA genes.

This is clearly a strong natural influence. But there are effects from nurture, or the environment, as well. High cadmium intake, especially through smoking, greatly increases the risk. In one study, smoking increased the risk of breast cancer about 30% in women with BRCA mutations.

In this example, the mutation (or genetic factor) plays a huge role. However, environmental influences like smoking, phthalate exposure, and hormone therapy can significantly impact whether or not the individual ever develops cancer.

Understanding Nature vs. Nurture

As a therapist, I’m asked about nature vs. nurture regularly. Clients ask me about it in relation to their experience, and people often casually ask about it when they find out I’m a therapist. It’s a bit of a frustrating question at times, as I find there is a real lack of understanding.

As I tried to demonstrate with the above examples of nature and nurture, it’s really a both/and rather than an either/or. They are indeed two different groups of factors, but they are not independent of one another. They go together to make the people we are.

Genetics: The Natural Side

The “nature” side of the nature vs. nurture debate is really just genetics. For example, twin studies suggest that 40-60% of an individual’s personality are inherited via genetics. This does not mean that things like your personality, intelligence, or mental health are set in stone from birth by any means.

What it does mean is that you inherit a fair portion of these qualities from your biological parents. These factors are out of your control and given to you at birth. However, the environmental side still has something to say about how you turn out!

Environment: Nurture’s Role

On the environmental side, or nurture, there are countless factors. I simply can’t list all of them here, but we can think of them in a few groupings.

Family and Childhood

Early childhood plays a huge role in the nurture side of the debate. Factors include parenting style, family conflict, financial stability, birth order, exposure to violence, and neglect or abuse. All of these aspects of childhood (and many more) play a role in how your genes are expressed.

Education and Stimulation

Especially when it comes to intelligence, educational opportunities and cognitive stimulation play an important role. These factors include the quality of schooling, teacher support, access to learning materials, attending preschool, and parental education.

Social Environment

One’s relationships with their peers or adults, especially in childhood, have a strong potential to shape us. For example, it’s believed that kids learn more from their peers in regards to problem-solving, empathy, and social norms than their parents by age 10-12. Factors include peer pressure, bullying, romantic relationships, and social support networks.

Culture and Society

Bigger-picture factors like the society one grows up in, religion, gender roles and expectations, societal attitudes toward mental health, and media exposure also play a big role in the nurture side of the debate. Where we grow up, our race or ethnicity, the political climate, etc. all influence our personalities, intelligence, and mental health.

Life Events

This is a vague section, but I wasn’t sure what else to call it. Any life event, especially a stressor, plays a role here. This includes loss of a loved one, illness or injury, displacement, or job loss. It also may include major transitions like marriage, divorce, parenthood, retirement, or moving out on your own.

Health and Lifestyle

Finally, one’s overall health and lifestyle play a role. The National Institutes of Health reports that green spaces and spending time outdoors may improve children’s mental health. Things like diet, exercise, sleep quality, and access to healthcare all are vital factors.

Gene Activation and Epigenetics 

Finally, when talking about nature vs. nurture, it’s worth investigating the role of gene activation and epigenetics. Gene activation is simply the process of having a gene turned on or off to make proteins. This can happen from a variety of factors.

Let’s take the example of cancer. You have many genes that help prevent uncontrolled cell growth, which protects against the growth of tumors and cancer. Environmental factors, such as smoking, can actually turn off that protective gene. This gives cells the ability to replicate and grow with less oversight, increasing the risk of developing cancer.

You can clearly see how your genetics here are influenced by the environment. In turn, your genetics are being expressed differently. The genes themselves are not changing; you still have that gene. It’s just a matter of whether or not it is turned on. It’s also important to note that genes are not black and white like this, and actually fall on a spectrum in their expression.

Then we have the role of epigenetics. Related to activation, epigenetics refers to how easy or hard it is to activate a gene. This is often caused through DNA methylation or histone modification, which I won’t go into here.

As an example, we can look at chronic childhood stress. Those who experience chronic childhood stress experience increased methylation on the NR3C1 gene. Because this gene is altered, fewer glucocorticoid receptors are produced as the individual grows. These receptors are for steroid hormones such as the aforementioned stress hormone cortisol.

Because the person has less receptors for these hormones, they have a lowered ability to manage stress. This is not a short-term effect and can impact the activation of other genes related to stress. Epigenetics means it is harder for the individual to regulate their stress as they simply don’t have the receptors.

What to Do with this Information

I see a lot of people use nature and nurture as a way to understand their experience. I think this can be valuable, but also may be unhelpful at times. We can use our genetics and environmental factors to understand what is present for us, but we also must be careful to not simply place the blame there and do nothing.

My encouragement in my clinical practice is often to look at the things we can control: the environment. Regardless of what hand we were dealt, we do have some agency to change the factors of nurture in our lives. Even if it may be difficult or take time, humans have an impressive ability to change brain chemistry and pathways.