The study, co-led by the Universities of Bristol and Michigan in the US, combined data from 46 studies, which the team used to study the 'big five' personality traits used in modern psychology – extraversion, agreeableness, conscientiousness, neuroticism, and openness to experience.
The team analysed the genes of more than a million people who had also completed personality questionnaires, identifying more than 1,200 genetic variants associated with the 'big five' personality traits.
The researchers found that these genetic influences were remarkably consistent across countries, age groups and different methods of measuring personality. Their findings also showed that personality is highly polygenic, meaning it is shaped by thousands of genetic differences, each contributing only a very small effect.
Extensive genetic overlap was found between personality, mental and physical health, education, employment, behaviour and residential choices. Further analysis suggested several potential causal relationships. For example, greater genetic liability to extraversion was associated with an increased risk of being infected with COVID-19, while conscientiousness was associated with lower body mass index, a reduced likelihood of starting smoking, and fewer hospital admissions.
However, the authors caveat that these causal findings require confirmation using further in-depth research.
Co-lead author Michel Nivard, Professor in Genetic Epidemiology from the MRC Integrative Epidemiology Unit and Population Health Sciences at the University of Bristol, said: "What is remarkable is not that we have found a 'gene for personality' - we have not, but that across more than a million people, different countries, different ages and many different questionnaires, we appear to be detecting the same underlying genetic influences.
"These genetic influences do not determine who we become. Instead, they give us a powerful new way to investigate why people differ so greatly in how they think, feel and behave, and how personality may in turn shape our health, relationships, choices and the environments we are drawn to."
The researchers also analysed genetic data from more than 51,000 relatives. By comparing family members, they could test whether genetic associations found in the wider population were distorted by differences between families, such as social background, geographical ancestry or parents passing both genes and environments to their children. Unlike findings for several other behavioural and social characteristics, the personality associations changed very little in these within-family analyses.
Professor Nivard added: "Personality develops through the concurrent influences of genetics, family and social environments, life experiences and our own choices. Our results describe patterns across very large groups; they cannot read an individual's personality from their DNA.
"These findings should not be used to assess people in employment, education, insurance or healthcare, if we want to know a person's personality, we can just measure their personality directly, there is no added value of genetics there. Rather the value of genetics of personality lies in helping researchers understand the biological and developmental pathways connecting personality with health and life outcomes."
A major next step will be to leverage these results to do fine grained analysis of the correlates and consequences of personality and eventually build on these results to investigate narrower characteristics within the Big Five, for example, distinguishing sociability from assertiveness within extraversion, and to include substantially more participants from globally diverse populations.
Paper
'Robust inference and correlates from genetic associations with personality', by T. Schwaba et al, in Nature [open access]
