A massive genetic study offers one of the clearest pictures yet of how DNA contributes to personality, identifying genetic variants associated with five major personality traits. However, rather than uncovering a handful of “personality genes,” the findings show that 1,260 different variants are associated with aspects of personality, which are influenced by thousands of genetic differences, each with a tiny effect.
The study, published recently in Nature , combined data from 46 research groups, with sample sizes ranging from 611,000 to 1.14 million people depending on which of the “Big Five” personality traits was analyzed: extraversion, agreeableness, conscientiousness, neuroticism or openness to experience. Of the 1,260 genetic variants identified, 824 were in regions not previously linked to the corresponding personality trait.
"There isn’t a single gene for being outgoing or conscientious,” said Henry R. Kranzler, MD , a professor of Psychiatry in the Perelman School of Medicine at the University of Pennsylvania, director of Penn’s Center for Studies of Addiction, and a co-author of the study. “What we see instead are thousands of genetic differences that individually contribute a small amount, but collectively shape personality, alongside the many influences of a person’s environment.”
Common genetic variants explained about 5 to 9 percent of the differences in personality measured in the study’s primary analysis. The researchers estimated that more than 16,000 common genetic variants independently contribute to each of the five personality traits, illustrating just how genetically complex personality is.
The genetic patterns also proved surprisingly consistent. Associations were generally similar across different age groups, Western geographic regions, personality tests, and how people described themselves or were rated by someone close to them. Agreeableness showed less consistency than the other traits.
The researchers went a step further by comparing people within families. Those analyses suggested that most of the genetic associations could not be explained by environmental factors shared among family members, a potential source of bias in studies connecting genetics with behavior.
The team also found genetic overlap between personality traits and a broad range of behaviors and health outcomes, including mental health conditions, substance use and physical health. For example, genetic profiles associated with neuroticism were associated with increased risk across the psychiatric conditions studied, while conscientiousness showed genetic associations with less substance use and more frequent exercise.
The associations are at the group level and cannot be used to make predictions about individuals. The researchers found that genetic measures predicted behavior only to a small degree and explicitly cautioned that they cannot predict an individual’s future behavior. Personality, in totality, reflects both genetic and environmental influences.
"These findings give us a new tool for studying why personality is connected to so many aspects of health and behavior,” Kranzler said. “But they also reinforce an important point: our DNA influences, but does not dictate our personality or our future.”
The researchers say larger studies encompassing more ancestral and cultural backgrounds will be important for determining how consistently these genetic patterns apply across populations.
Editor’s Note
The research was supported by multiple funding sources, including grants from the National Institute of Mental Health and National Institute on Aging.
Nature