How genes shape personality traits: New links discovered

It’s long been known that DNA plays a role in shaping personality. Now, researchers at the Yale School of Medicine (YSM) have taken another step toward determining precisely how this happens by identifying a number of new genetic sites associated with specific personality traits. They published their findings in Nature Human Behavior.

Using data from the Million Veteran Program, researchers conducted a genome-wide association study (GWAS) to identify genetic variations, called loci, associated with each of the Big Five personality traits: extraversion, openness, agreeableness, neuroticism, and conscientiousness. The researchers then combined this data with previous GWAS studies to conduct a meta-analysis of nearly 700,000 people, the largest GWAS of personality traits to date.

“We’re one step closer to this process of increasing the sample size to be able to understand more clearly which variants are really linked to these personality traits,” says Daniel Levey, Ph.D., assistant professor of psychiatry at YSM and the study’s principal investigator.

The Big Five and the new places

The Big Five personality traits are a scientific measure of personality that can be studied using self-reported assessments of whether people score high or low on each of the five traits. Participants in the Million Veteran Program, a national research program that collects data, including genetic information, from veterans to better understand genes and health, completed these assessments in addition to providing a blood sample for genetic analysis.

By comparing the results of the personality assessment with analysis of variations in the participants’ DNA, Levey and his team discovered 62 new loci associated with neuroticism. They also identified agreeableness loci for the first time. Combining their results with previously published data, they conducted a meta-analysis to identify more than 200 genetic loci spread across the five personality traits.

Despite the large number of genetic variations they have discovered, Levey hopes they can expand these studies in the future, possibly increasing the number of participants to millions of people rather than hundreds of thousands and also increasing the diversity of participants. Current studies of genes and personality have largely been conducted on people of European descent.

“To be able to say with certainty what direction these variations are in and what the actual precise effect of the variation is, we need to have much larger samples,” Levey says.

“Current studies of human genetics are homogeneous compared to global populations. If we could include more diverse people and look at how associations between one population and another overlap, we would have a more precise definition.”

Genes, personality and mental health

Levey and his team also studied genetic correlations between personality traits and various mental health disorders. They found that there was a strong overlap between neuroticism, a personality trait marked by negative feelings, and depression and anxiety.

People with high agreeableness, a personality trait characterized by a tendency to get along well with others, were less likely to suffer from these disorders. These associations are already well understood from a psychiatric perspective, but Levey’s findings provide additional genetic support.

Priya Gupta, Ph.D., a postdoctoral researcher in Levey’s lab and first author of the manuscript, says that “although genetics is largely beyond our control, gaining a deeper understanding of our personality traits can help us become more aware of potential mental health risks and develop effective coping strategies to address those risks.”

But just because there is a genetic basis for associations between personality traits and certain mental health problems doesn’t mean those associations last a lifetime, Levey says.

“Your personality adapts and changes over time, so there’s a temporal relationship that we don’t necessarily capture with the cross-sectional way that we look at personality in our study,” he says. “Just because we find these genetic variations doesn’t mean that these are things that are inevitable and that you can’t change in your life.”

Levey hopes that personality studies like these could one day be useful in informing early treatment of mental health problems.

“When you look at those personality traits that are more predisposed to later developing mental illness, that might be a prodrome (a period of subclinical symptoms), look at who might be at higher risk, and then maybe that might be a reason for intervention,” he says.

“Even though we can genetically measure associations with traits like neuroticism, that doesn’t mean you can’t change your coping strategies in ways that help you perform better.”