Massive study reveals how your DNA is linked to your personality, health and even where you live

Why do some people exercise regularly while others struggle to stick to a routine? Why are some people naturally night owls, while others are active early in the morning? And why do some people gravitate toward bustling cities while others prefer quiet suburbs?

The answers may have something to do with our DNA.

In one of the largest studies of its kind, researchers analyzed the genetic information of more than a million people and identified 1,260 genetic variants linked to personality. Even more surprising, they found that some of these same genetic patterns were also associated with health, daily habits, career, and even where they chose to live.

In other words, it appears that the biological roots of personality may extend much further into our daily lives than previously thought.

At the same time, you should not read too much in this. Our genes may push us toward certain personality traits and behaviors, but they do not determine who we ultimately become as adults. Our experiences, our education and our environment still matter enormously.

What scientists have discovered about personality genetics

The idea that genes influence personality is neither new nor particularly revelatory. Among psychologists, it is an established fact that personality is partly inherited. Most of the early evidence came from studies comparing identical twins, who share virtually all of their DNA, with fraternal twins, who share about half of their variable DNA. Researchers have consistently found that identical twins tend to have more similar personalities.

A 2015 review of studies involving more than 100,000 people estimated that genetic differences account for 20 to 40 percent of personality variation within a population.

But identifying the actual genetic differences involved, down to naming and locating individual genes, has proven extremely difficult.

The new study, led by psychologist Ted Schwaba of Michigan State University, brought together information from 46 research groups around the world. Participants provided DNA samples and answered questionnaires measuring five broad personality traits, commonly known as the Big Five.

These include extroversion (how outgoing and sociable you are), agreeableness (how cooperative and compassionate you tend to be), conscientiousness (how organized and disciplined you are), neuroticism (how prone you are to worry and negative emotions), and openness to experience (how curious and interested in new ideas you are).

By comparing millions of genetic differences with individuals’ personality scores, researchers identified 1,260 significant associations. Of these, 824 were in regions of DNA not previously linked to the corresponding personality trait.

However, no single variant has had much influence on its own.

“There is no single ‘personality gene,’” Schwaba emphasizes.

Instead, personality appears to reflect the combined influence of thousands of genetic differences, each making a tiny contribution.

In the new study, the genetic differences examined by the researchers explained about 5 to 9 percent of the variation in individuals’ personality scores. That’s far lower than the 40 to 60 percent estimated by previous twin studies. But the two approaches measure different things. Twin studies estimate the overall influence of inherited genetic differences, including those that scientists have not yet identified. The new study measured only the effects of common genetic variants that current DNA analyzes can detect.

The researchers also wanted to make sure these genetic links didn’t simply reflect family upbringing. To test this, they compared parents, including twins who grew up in the same household but inherited different combinations of genes. Genetic links to personality have remained largely consistent. This suggests that the associations reflect true genetic influences rather than simple shared family circumstances.

However, this is not to say that education or life experiences are unimportant. They still play a major role in personality formation.

Your Personality Genes May Also Influence Your Health and Habits

Perhaps the most interesting finding is that genetic patterns associated with personality also appear in other aspects of people’s lives.

For example, people with genetic profiles associated with greater conscientiousness tend to exercise more often, use fewer addictive substances, and stay in the hospital less. They also tended to be more physically active during the day.

Meanwhile, genetic patterns related to openness to experience were associated with greater nighttime activity.

Researchers have also discovered links to mental health. Genetic profiles associated with neuroticism – a tendency to experience anxiety and emotional distress – overlap with increased vulnerability to several psychiatric disorders.

Even infectious diseases, among other things, have entered the picture.

People whose genetic profiles were associated with greater extroversion were more likely to be infected with COVID-19 early in the pandemic. One possible explanation is that extroverted people might have had more social contacts, thus increasing their opportunities for exposure.

Using information from more than 419,000 participants from the UK Biobank, researchers found that people with genetic profiles linked to greater openness were more likely to settle in cosmopolitan urban neighborhoods as adults. Those whose profile is linked to greater conscientiousness are more likely to settle in affluent suburbs.

Our personality can help determine the environments we seek out, while those environments can, in turn, strengthen certain aspects of our personality. You can see how difficult it can be for scientists to sort out the two, in a chicken-or-the-egg fashion.

“Personality seems to be relevant almost everywhere you look,” Schwaba said.

Could a DNA test tell you what kind of person you are?

Not reliable, at least for now.

Although researchers have identified hundreds of previously unknown genetic links, their combined effects remain too small to accurately predict an individual’s personality.

A person carrying genetic variants associated with extroversion might still be quiet and reserved. A person with genetic variants associated with neuroticism is not destined to develop anxiety or depression. Here we are talking about trend lines and statistical associations, which make sense for a large population but lose their predictive value when referring to a single person like you or me.

“Our DNA influences, but does not dictate, our personality or our future,” said Henry Kranzler, a psychiatrist at the University of Pennsylvania and co-author of the study.

The new results were published in September in the journal Nature.