Genes Linked to Personality Reveal a Complex Picture
Genes linked to personality have been identified in one of the largest studies ever conducted on human personality and genetics, giving scientists a clearer picture of how DNA may influence the way people think, feel and behave.
Researchers analyzed genetic and personality information from approximately 1.14 million people across 46 studies in 13 countries. The international research team identified more than 1,200 genetic variants associated with the major dimensions of human personality. The findings were published in the scientific journal Nature.
The discovery is significant because personality has long been considered a product of both nature and nurture.
Scientists have known from twin and family studies that genetics contributes to personality. However, identifying the specific genetic variants involved has been difficult.
The new research provides a much larger and more detailed genetic map.
At the same time, researchers emphasize an important limitation: there is no single gene that determines whether someone is outgoing, organized, anxious, agreeable or open to new experiences.
Instead, personality appears to emerge from the combined influence of many genetic variants, each generally having a very small effect, together with environment, experiences and individual choices.
More Than 1,200 Genetic Variants Were Identified
The headline number from the study is striking.
Researchers identified more than 1,200 genetic variants associated with the Big Five personality traits. According to the University of Bristol, the study included genetic information from more than one million people and combined data from 46 separate research cohorts.
Some of these variants had been associated with personality in earlier research.
Many others were identified for the first time.
This was possible because the researchers combined large datasets instead of relying on relatively small individual studies.
Large genetic studies are particularly important for personality research because the influence of any individual genetic variant tends to be extremely small.
A study involving a few thousand participants might not have enough statistical power to detect those subtle effects.
With more than one million participants, researchers could search for much smaller and more reliable genetic associations.
The result is a broader picture of how biological differences can contribute to personality.
What Are the Big Five Personality Traits?
The researchers focused on the widely used Big Five model of personality.
The five traits are:
- Extraversion — tendencies related to sociability, energy and engagement with other people.
- Agreeableness — tendencies involving cooperation, compassion and interpersonal warmth.
- Conscientiousness — tendencies involving organization, responsibility and self-control.
- Neuroticism — tendencies involving emotional sensitivity and vulnerability to negative emotions.
- Openness to experience — tendencies involving curiosity, imagination and interest in new ideas and experiences.
These traits are not simple categories.
A person is not simply “an extrovert” or “an introvert” in the way a person might belong to a blood group.
Instead, people can fall at different points along each personality dimension.
Someone might be highly conscientious while also being relatively introverted, for example.
The new genetic study examines how variations in DNA relate statistically to those differences.
Genes Linked to Personality Do Not Determine Who You Are
Perhaps the most important message from the research is what the findings do not mean.
The discovery of genetic variants associated with personality does not mean scientists can look at someone’s DNA and accurately determine their personality.
Researchers involved in the project specifically caution against interpreting the findings as a genetic personality test.
University of Bristol researchers stressed that personality develops through the combined influence of genetics, family and social environments, life experiences and personal choices.
That distinction matters.
Genes can influence biological processes that affect behavior and temperament. But the relationship between DNA and personality is extremely complicated.
A genetic variant may slightly change the probability of a particular behavioral tendency without determining how an individual will behave.
The person’s environment can then influence how that tendency develops.
Education, friendships, culture, socioeconomic circumstances, experiences and personal decisions can all contribute to the final result.
Therefore, genetic influence should not be confused with genetic destiny.
The Genetic Effects Are Relatively Small
The study found that common genetic variants explained only a fraction of the differences in personality between individuals.
One analysis reported that the variants accounted for roughly 4.8% to 9.3% of individual variation, depending on the personality trait.
That number is important.
It means genetics matters, but the identified common variants explain only part of the overall picture.
Researchers have previously estimated substantially larger heritability levels using twin studies. Those estimates capture genetic contributions more broadly, including effects that may not be detectable through the common variants examined in this type of genome-wide study.
The difference highlights how complicated genetic architecture can be.
There is also a major distinction between heritability and the amount of variation explained by particular genetic markers.
Heritability is a population-level statistical measure. It does not mean that a certain percentage of an individual’s personality is “genetic.”
The new findings therefore add another layer to the scientific understanding of personality rather than settling the nature-versus-nurture debate.
No Single Personality Gene Was Found
The idea of a single “personality gene” may sound appealing, but the evidence does not support it.
Instead, the research points toward a highly polygenic model.
Polygenic means that many genetic variants contribute to a characteristic.
Each individual variant can have an extremely small effect.
Together, however, thousands of variants may contribute to measurable differences across a population.
This pattern is common in complex human characteristics.
Height, educational outcomes and many health-related traits are also influenced by large numbers of genetic variants rather than a single gene.
Personality appears to follow a similar pattern.
That makes genetic prediction much more complicated than simply finding one DNA sequence associated with being outgoing or cautious.
Genes Linked to Personality Also Relate to Health
One of the most intriguing findings was that genetic associations with personality overlapped with genetic factors associated with other areas of life.
The researchers examined relationships between personality-related genetic variants and outcomes involving mental and physical health, education, employment, behavior and residential choices.
This does not mean that personality genes directly cause all of those outcomes.
Instead, the researchers found patterns of genetic overlap.
For example, genetic factors associated with conscientiousness were linked with several health-related outcomes, including lower body mass index, a lower likelihood of starting smoking and fewer hospital admissions.
Extraversion-related genetic liability was also associated with an increased likelihood of COVID-19 infection in one analysis.
These relationships are scientifically interesting because personality can influence behavior.
Someone who tends to be more conscientious may be more likely to follow routines, avoid certain risky behaviors or maintain health-related habits.
However, the genetic findings do not mean that a person’s DNA directly determines whether they will smoke, become ill or succeed in school.
Those outcomes involve numerous biological and environmental influences.
Personality May Influence Where People Live
Another surprising result involved residential choices.
The research found genetic associations between openness to experience and a tendency to live in more cosmopolitan neighborhoods.
At first, that might sound like a straightforward genetic effect.
But the researchers point to a much more interesting possibility.
Personality can influence the environments people choose.
Those environments can then influence personality.
For example, a person who enjoys novelty and cultural diversity may be more likely to choose a large, cosmopolitan city.
Living in that environment may then provide additional experiences that reinforce certain aspects of openness.
This creates a feedback loop between biology, behavior and environment.
In other words, the relationship is not simply:
Genes → personality → life.
It can also involve:
Genes → personality → choices → environment → personality development.
That interaction is one reason researchers say the traditional “nature versus nurture” debate is too simplistic.
Family Environment Was Not the Whole Explanation
The researchers also performed analyses involving more than 51,000 relatives.
Family-based comparisons can help scientists determine whether apparent genetic associations are actually being produced by environmental differences shared by families.
For example, families can share neighborhoods, socioeconomic circumstances, educational opportunities and cultural environments.
If a genetic association disappears when researchers compare relatives, that can suggest that environmental or family-level factors contributed to the original finding.
In this study, the personality associations changed relatively little in within-family analyses, according to the University of Bristol.
That strengthened the researchers’ confidence that the genetic associations were not simply artifacts caused by differences between families.
However, it still does not mean that environmental influences are unimportant.
Quite the opposite.
The researchers continue to emphasize that personality emerges through multiple interacting forces.
Genes Linked to Personality Can Be Studied Across Ages
Another strength of the research was its scale across different populations and age groups.
Researchers found that some genetic associations were consistent across countries, ages and different approaches to measuring personality.
Michigan State University researchers gave an example involving extraversion: genetic variants associated with the trait in young adults in the Netherlands also predicted differences in extraversion among older adults in the United States.
This kind of replication is important.
A genetic association found in one population can sometimes fail to appear in another.
When similar relationships are detected across different datasets, researchers gain greater confidence that the findings reflect a real biological association rather than a statistical accident.
Still, researchers say much more work is needed to ensure that genetic findings apply to populations around the world.
The Study Has Important Limitations
Despite its size, the research has limitations.
One major issue is that genetic studies have historically relied heavily on participants of European ancestry.
If certain populations are underrepresented, researchers may not be able to determine whether the same genetic associations apply equally to people from different ancestral backgrounds.
The researchers identified greater global diversity as an important direction for future studies.
Another limitation is that genetic association does not automatically establish causation.
If a genetic variant is associated with a personality trait and that trait is associated with another outcome, researchers cannot automatically conclude that the DNA directly caused the outcome.
Biological pathways can be complicated.
Genes may influence multiple traits.
Traits can influence behavior.
Behavior can influence environments.
And environments can influence development.
Untangling those relationships requires additional research.
Could DNA Eventually Predict Personality?
The new findings naturally raise a provocative question: Could a DNA test eventually predict someone’s personality?
The researchers are cautious.
The current evidence does not support using genetic information to determine an individual’s personality with high accuracy.
The genetic effects identified are too small and distributed across too many variants.
Personality is also shaped by experiences that cannot be read directly from DNA.
A genetic score may predict statistical tendencies across large groups, but that does not make it a reliable personality assessment for one individual.
In practical terms, researchers say that if someone wants to know a person’s personality, directly measuring personality is more useful than analyzing their genetics.
That point is particularly important for employment, education, insurance and healthcare.
Using genetic information to make judgments about a person’s character could create serious ethical and social problems.
What the Discovery Could Mean for Science
Although the findings do not provide a genetic personality test, they could be valuable for scientific research.
Personality is associated with many aspects of human life.
It can affect behavior, relationships, education, work, health and lifestyle.
Understanding the biological pathways associated with personality could therefore help researchers understand why certain outcomes tend to occur together.
The study may also help researchers investigate more specific characteristics.
The Big Five are broad dimensions.
Extraversion, for example, includes multiple aspects of behavior.
A future study could examine whether the genetic factors associated with sociability are different from those associated with assertiveness.
Similarly, openness may contain several distinct psychological characteristics.
Breaking broad traits into narrower components could reveal more precise biological relationships.
Researchers Want More Diverse Genetic Data
The next stage of the research will involve expanding the populations included in genetic studies.
The researchers say substantially more participants from globally diverse populations are needed.
That would help determine whether the associations discovered in this study are broadly applicable.
It could also improve scientists’ understanding of how genetic variation interacts with different environments.
This matters because genes do not operate in isolation.
The same genetic variant can potentially have different effects depending on environmental circumstances.
Studying more diverse populations could therefore reveal additional biological and environmental pathways.
Genes Linked to Personality Change the Nature-Nurture Debate
For generations, scientists and the public have debated whether personality is primarily inherited or shaped by experience.
The new study suggests that this is the wrong way to frame the question.
Personality is not simply genetic.
It is not simply environmental.
Instead, biology and experience interact throughout development.
Genetic differences can influence tendencies.
Those tendencies can influence the environments people seek.
Those environments can then reinforce or modify behavior.
Personal choices can add another layer.
The result is a dynamic process rather than a fixed genetic program.
This is arguably the most important lesson from the research.
Genes Linked to Personality: What We Know Now
The new study provides several important conclusions.
First, researchers identified more than 1,200 genetic variants associated with the Big Five personality traits.
Second, the findings were based on an enormous dataset involving about 1.14 million people across 46 studies.
Third, the associations were replicated across different countries, ages and measurement methods.
Fourth, the identified genetic variants also showed relationships with health, education, employment, behavior and other life outcomes.
Fifth, the study found no single gene responsible for personality.
Sixth, the genetic variants explain only a relatively small portion of individual personality differences.
Finally, researchers emphasize that genetics does not determine an individual’s personality.
The findings instead reveal how biological variation contributes to a much larger system involving environment, experiences and personal decisions.
A New Chapter in Personality Science
The discovery of genes linked to personality represents an important advance in behavioral genetics.
The sheer scale of the study allowed scientists to identify genetic associations that would have been difficult to detect using smaller datasets.
But perhaps the most interesting result is not the number of genetic variants.
It is the complexity revealed by those variants.
Human personality cannot be reduced to a DNA test.
There is no single “extrovert gene.”
There is no single “kindness gene.”
There is no single genetic switch that determines whether someone is responsible, anxious, curious or sociable.
Instead, thousands of genetic differences may contribute tiny influences that interact with one another and with the world around us.
That means two people with similar genetic tendencies can still develop very different personalities.
Their experiences, relationships, choices and environments matter.
The research therefore adds weight to a more nuanced understanding of human behavior.
Our DNA is part of the story.
It is not the whole story.
As scientists expand genetic studies to include more diverse populations and examine increasingly specific personality characteristics, researchers may gain an even clearer understanding of how biology and experience combine to shape human behavior.
For now, the central message is straightforward: genes linked to personality can help explain why people differ, but they do not define who people are.
