When it comes to personality, humanity contains all sorts, from people who thrive on socializing to those who’d prefer to have a quiet cup of tea at home. Psychologists have found that five dimensions of personality, often termed the “Big Five,” are reliable descriptors of temperament. Given regular questionnaires about their lives and attitudes, people tend to score consistently across their lifetimes on extraversion, openness to experience, agreeableness (a tendency to go with the flow), neuroticism (a tendency toward anxiety and other negative emotions), and conscientiousness (like self-discipline and rule-following).
Exactly how these tendencies arise, and the extent to which they are the result of nature or nurture, are areas of active research. Now, in a paper published in Nature on September 2, scientists who examined the genes of more than a million people who also took personality questionnaires have revealed a swath of genetic variants linked to each of the Big Five traits. This information opens the door to research into the intersection of personality and biology, helping to answer questions about how we become who we are.
Psychologists have long suspected that some aspects of personality must be genetic, says Denis Bratko, a psychologist at the University of Zagreb in Croatia who has studied this question but was not involved in the new research. Previous efforts to look for these links, however, did not uncover clear correlations—no particular gene or genes for extraversion, for example—likely because study sizes were small and because there are now thought to be many genetic variants, each with a subtle effect, involved in personality. “Several decades of studies have seen failures because they [have been] looking for one or a few genes which will have a huge effect,” he says.
To overcome these problems, the authors of the new study reached out to scientists around the world who manage repositories of data that include both genomic information and information about personality.
“We think that personality is super-important for health,” says Michel Nivard, a professor of genomic epidemiology at University of Bristol in the U.K. and an author of the study. Scores on Big Five traits have long been associated with risk for mental-health diagnoses; neuroticism, in particular, is linked to anxiety. Personality can also help predict certain health outcomes, including whether people will stick with taking medication or seek out medical help for a problem.
The study revealed more than 1,000 genetic variants that appear to contribute to personality. Because the data came with all sorts of information about the people in the study—including, in some cases, the area where they lived, how much they walked a day, how other people rated them on personality questionnaires, and other measures—the researchers could see links between personality traits, genetic variants, and other parts of people’s lives as well.
Looking at genetic profiles, the researchers could see that people whose variants were linked to extraversion were more likely to be infected with COVID early in the pandemic, says Nivard. “Which makes sense, right? Because when you loosen up rules around social interaction, then the people who will take advantage of those loosening rules the most are people who have been missing that interaction most,” he says.
Personality was also linked to where people lived in midlife, the researchers found, using information from the UK Biobank that included home location. Those with genetic profiles linked to greater openness to new experience tended to end up in cosmopolitan cities, while those higher on neuroticism gravitated to affluent suburbs.
Overall, the study found that a relatively small but significant proportion of personality can be predicted by genetics—up to around 13%—reinforcing psychologists’ impression that personality is a combination of genetics and environment. And it’s not necessarily the case that personality is inherited: an extravert, for example, may not have extraverted children. The system is clearly quite a bit more complex than that.
Many, many genes—more than were identified in this study—are probably involved, influencing a variety of pathways in the brain, Nivard says. “That must be the case, given how diffuse we find those genetic effects to be.”
“It's a wonderful paper,” says Tena Vukasović Hlupić, a psychologist at the University of Zagreb who was not an author on the new study. “It's finally empirical evidence that there is not one gene for whatever personality trait.”
Understanding the genetic variants playing into each trait may help psychologists and neuroscientists further explore the basic neurobiology of personality. “There’s this endless debate on whether our body and our experiences shape our personality, or whether personality shapes our experience. I'm super excited to go and use these results to dig into those kinds of questions,” says Nivard.
This information also raises the possibility of using such variants as a way to screen for problems down the road, says Hlupić. The variants themselves are only a small part of what might give people a predisposition to a certain mental-health condition, for instance, but if they can be used as an indicator of risk, and early interventions can help, they might be useful tools beyond basic research.
If you’d like to find out more about your own personality, the best way is still an academically validated Big Five test, Nivard says—not a genomic test. “There is no better way to know about your personality than to take a personality test,” says Nivard. “They're really good. They're not perfect, but they're way better than anything we could ever do with genetics.”
