The genetics of one's personality, or gene variants that predict it, could be more relevant to human experience and associated with health, education, career paths, among other major life outcomes, new research suggests. An international team of researchers forming the Revived Genomics of Personality Consortium combined results from 46 distinct cohorts around the world to study the genetic basis of personality. Findings published in the journal Nature show that more than 1,200 gene variants are associated with the Big Five personality traits -- openness, conscientiousness, extraversion, agreeableness and neuroticism -- and that the personality genetics are linked to dozens of life outcomes, including health behaviours.

The DNA of two randomly selected people is approximately 99.9 per cent identical -- differences in the remaining 0.1 per cent of the genome can influence individual traits, including appearance, disease risk, and the body's response to medications, the researchers said.

The small amount of genetic variation may also be linked to several personality traits, they found.

The authors wrote, "(Genetic) analyses indicate that personality traits have widespread, potentially causal associations with consequential behaviours and life outcomes." "There is no single 'personality gene'," lead author Ted Schwaba, faculty at Michigan State University's Department of Psychology, said.

"Personality traits are associated with many genetic variants, but even the largest effects of individual genetic variants are still very small. However, even though any individual genetic variant makes very little difference in personality, the effects of many variants together can be more sizeable," Schwaba said.

For example, the same variants linked to extraversion in a young adult in the Netherlands also predicted extraversion in an older adult retiree in the US, the study found.

The researchers used methods that compared relatives to one another and "confirmed" that the genetic links weren't actually the byproduct of a shared upbringing.

However, despite the genetic associations, environment was still found to play a major role in personality.

For example, the study found that common genetic variants linked to openness to experience predicted that a person would move to more cosmopolitan neighbourhoods. In turn, living in those neighbourhoods may reinforce and further shape that same trait.

The researchers noted that the genetics of personality are relevant to many parts of the human experience.

The genetic variants that predict personality can also partially predict mental and physical health, longevity, education, career paths and outcomes and even how people are perceived by close others, they said.

Genetic variants linked to conscientiousness were associated with being more active during the day, while variants linked to openness to experience and extraversion were linked to being more of a night owl.

"Personality seems to be relevant nearly everywhere you look. We hope this study will encourage many other scientists to incorporate personality traits into their fields of study," Schwaba said.

"For example, genetic variants associated with neuroticism predict more time spent in the hospital, which is relevant to physicians and health researchers, and variants associated with openness to experience are linked to income and switching jobs, which is relevant to vocational researchers," Schwaba said.

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