Why are some people more curious, organised or compassionate than others? Huge genetic study uncovers over 1200 variants linked to personality while highlighting the power of environment

Why is one person naturally drawn to crowds while another would rather spend an evening alone? Why does one individual meticulously plan everything while another thrives on spontaneity? And why do some people seem more emotionally reactive, curious or trusting than others?

For decades, psychologists have studied these differences through personality traits. Now, a huge international genetics study is adding another layer to the picture: some of the variation in personality is linked to differences in our DNA, but the genetic contribution is spread across thousands of tiny effects rather than controlled by a handful of “personality genes.”

The findings, published September 2, 2026, in Nature, come from one of the largest genetic investigations of personality so far. Researchers combined data from 46 cohorts involving between 611,037 and 1.14 million participants, depending on the personality trait being analysed.

The Big Five provide the map

The researchers focused on the widely used Big Five model: extraversion, agreeableness, conscientiousness, neuroticism and openness to experience.

These dimensions describe broad tendencies rather than rigid categories. Extraversion encompasses characteristics such as sociability and assertiveness; agreeableness includes compassion and trust; conscientiousness relates to organisation and responsibility; neuroticism captures tendencies toward anxiety and emotional volatility; and openness includes curiosity, imagination and sensitivity to new experiences.

The model has become one of the most influential frameworks in personality psychology because it allows researchers to describe individual differences without reducing people to simplistic types.

More than 1,200 genetic variants enter the picture

In the new study, Ted Schwaba, Margaret L. Clapp Sullivan, Elliot M. Tucker-Drob and colleagues, working through the Revived Genomics of Personality Consortium, identified 1,260 genetic variants associated with one or more of the Big Five traits. Of these, 824 had not previously been identified in earlier work, according to the researchers.

The results substantially expanded the number of genetic associations detected for individual traits. The study increased identified loci associated with conscientiousness from three to 131, extraversion from 14 to 258 and neuroticism from 224 to 706.

But the numbers should not be mistaken for a genetic blueprint.

There is no single ‘personality gene’

One of the most important findings is how small the influence of individual genetic variants is. The study estimated that common genetic variants accounted for roughly 4.8% to 9.3% of variation in the measured Big Five traits, rising to about 9.3% to 13.3% when using personality measures with typical levels of measurement reliability.

The researchers therefore describe personality as having a highly distributed genetic architecture. Instead of one gene determining whether someone is outgoing, anxious or conscientious, many variants appear to contribute extremely small effects.

A 2026 review in Gene reaches a broadly compatible conclusion, noting that personality's genetic architecture involves many variants with small individual effects, while environmental factors account for substantial remaining variation.

What about the family you grow up in?

This is where the study becomes particularly interesting. Because family members share both genes and environments, genetic studies can sometimes struggle to determine whether an apparent genetic association is actually being produced by the environment surrounding a child.

The researchers therefore conducted within-family analyses, including comparisons involving relatives. They found relatively little evidence that shared family environments were driving the genetic associations they observed for personality. The study also reported minimal evidence that people tend to select spouses with personalities similar to their own.

That does not mean family life is irrelevant to personality. The researchers explicitly state that personality remains substantially influenced by environmental factors.