Identical twins possess near-identical genetics yet can develop distinct personalities, offering a demonstration that DNA is not destiny. However, a portion of human identity is written in genetic code, raising the question of how closely DNA and personality are linked. The largest genetic investigation of the Big Five personality traits to date has identified more than a thousand genetic variants associated with the ways individuals think, feel, and behave, according to findings reported by ScienceAlert.
Massive Investigation Reveals Extent of DNA’s Role in Human Personality
Researchers brought together personality and genetic data from 46 cohorts, with the largest analysis encompassing approximately 1.14 million people. The team focused on the Big Five dimensions used by psychologists to describe personality: extraversion, agreeableness, conscientiousness, neuroticism, and openness to experience. Through genome-wide association studies, or GWAS, investigators searched genomes across vast numbers of people for variants that consistently appeared alongside differences in those traits.
Understanding the Big Five and Genetic Complexity
Personality is defined by psychologists as encompassing traits, adjectives used to describe individuals such as creative, hard-working, honest, and kind. According to experts, personality also involves identity, life story, reputation, and how others perceive a person, alongside skills, abilities, interests, and motivations. The Big Five framework scores individuals along five broad traits, letting researchers compare personalities across people and over time. These measures have proven consistent predictors of school and work performance, relationships, health, and longevity.
Rather than searching for a single definitive gene for traits like extraversion or neuroticism, scientists anticipated a complex genetic architecture. Nivard noted that there are no genes with an effect perceptible at an individual level in the way that genetic outcomes exist for conditions like Alzheimer’s. Elliot Tucker-Drob of the University of Texas at Austin serves as a co-senior author of the research.
Modest Influence and Limitations in Individual Prediction
The analysis identified 1,260 lead genetic variants associated with the Big Five personality traits, including 824 variants that had not been previously linked to them. Despite the large number of variants involved, DNA explains only a modest proportion of personality differences between individuals. Across the Big Five traits, the genetic variation captured by the study accounted for roughly 7.4 to 10.6 percent of those individual differences.
Knowing an individual’s genetic variants was found to be unhelpful for predicting personality. When researchers used genetic information to make predictions in separate groups, the models could explain less than 4 percent of the variation in personality. Consequently, genetics cannot reliably determine an individual’s personality. As Nivard stated to ScienceAlert, measuring personality directly provides a clear picture, whereas genetics does not add anything useful on an individual level. Instead, genetics offers a way to link personality in the aggregate across groups of people to other outcomes.
Context from Twin Studies and Environmental Factors
Historical research provides additional context on heritability. Throughout the 20th century, twin studies examined how genes and environment shape personality. A 1996 study comparing 123 pairs of identical twins with 127 pairs of fraternal twins found that genetic differences accounted for roughly 40 to 60 percent of variation across the Big Five traits, an estimate supported by a 2015 meta-analysis of more than 100,000 people showing personality is about 40 percent heritable.
Behavioral geneticist Matthew Keller of the University of Colorado Boulder notes that heritability measures the proportion of variation linked to genetics across a population rather than dictating a fixed percentage of an individual’s personal traits.
