Personality plays into how people think, feel, behave and interact with their environment.Credit: PeopleImages/Getty
A study of more than one million people has uncovered around 1,200 genetic variants that are associated with personality traits, and is by far the largest effort of its kind.
The researchers found that common genetic variants account for a small percentage of variation in the ‘Big Five’ personality traits — extroversion, agreeableness, conscientiousness, neuroticism and openness to experience — within a population.
Although the genetic links to personality are small, the study found that they are more robust to confounding factors such as family background than are gene associations with education level, income and some other socio-behavioural traits. Using these genetic correlations, the researchers connected personality traits to a slew of health and lifestyle factors, including whether a person is likely to take up smoking (linked to how conscientious they are), COVID-19 infection risk (linked to extroversion) and even participation in research studies (linked to a person’s agreeableness and openness to experience).
“Personality is super central to all kinds of human outcomes,” says Michel Nivard, a genetic epidemiologist at the University of Bristol, UK, who co-led the study, which was published on 2 September in Nature1. It is not yet clear whether personality underlies such differences, however. “We just want to show that the genome can be used to start to study those,” he adds.
“Researchers in the field have been waiting for a sufficiently large genome-wide association study, or GWAS, of personality,” says Aysu Okbay, a behavioural geneticist at Amsterdam University Medical Centre. “Genetic studies of personality have lagged behind those of many other important behavioural traits.”
Big personality data
Like all human characteristics, personality is influenced by the interplay between a person’s genetic make-up and environmental influences. But efforts to identify reproducible gene variants linked to personality have been hampered by the absence of reliable measurements of personality in many of the large population genomic databases.
To overcome this, an international effort called the Revived Genomics of Personality Consortium pooled data from 46 cohorts representing between 611,000 and 1.14 million people, depending on the trait.
All the participants had completed questionnaires (such as this one from PersonalityLab.org) that psychologists use to measure the Big Five traits and the individual characteristics that comprise each one. The researchers note in an accompanying FAQ document that the tests are not the only way to measure personality, and scientists continue to debate how effective they are at capturing it. But they remain widely used in psychological research.
Ambitious survey of human diversity yields millions of undiscovered genetic variants
The researchers found 1,260 common genetic variants associated with one or more of the Big Five traits, including more than 800 that had not been previously identified. The study increased the number variants linked to conscientiousness from 3 to 131 and, for neuroticism, from to 224 to 706. Depending on the personality trait and analytical variables, common genetic variants explained between about 5% and 16% of the variation across participants.
Individual variants tended to exert only a tiny influence on personality, the researchers emphasize. The average variant linked to greater extraversion, for instance, would explain the difference between sitting at the 50.35th percentile for the trait and the 50th.
Moreover, says Nivard, there is little point in trying to predict an individual’s personality from their genetic make-up. “I’m not in the business, or interested at all, in predicting personality. Because if I want to know personality, I would just measure it,” he says.
In separate analyses involving participants who were related, including comparisons between twins, and between parents and siblings, the researchers found little sign that a shared family environment was behind the genetic associations for personality.
“I figured there would be some of that going on, some indirect genetic effects, where your early environment, shaped by the genes in your parents, would influence your personality,” says Nivard. “We just don’t find that kind of gene–environment correlation.” The study also found little evidence that people choose spouses who have similar personalities to their own.