Million-Person Study Maps Genetic Footprint of Personality

An international analysis of up to 1.14 million participants identified about 1,260 genetic variants linked to the Big Five personality traits (extraversion, agreeableness, conscientiousness, neuroticism, openness), vastly expanding prior findings with roughly two-thirds newly discovered. Common variants explain only about 5–9% of personality variation (around 13% when accounting for measurement error), far below the 40–60% heritability suggested by twin studies, highlighting the substantial role of environment and genetic complexity. Signals are broadly consistent across populations, ages, and measurement methods, though agreeableness shows more variation. The study connects personality patterns to a wide range of life outcomes and, using Mendelian randomization, provides evidence that personality can causally influence outcomes like body weight, smoking, and COVID-19 risk, while educational and other life circumstances can shape personality over time. Importantly, individual genetic effects are tiny and cannot predict a person’s character; environment remains a major driver of who people become.