A study published in Political Behavior shows how genetic scores related to health and psychological traits can predict a person’s likelihood of voting or engaging in politics. Analyzing genetic data from more than 50,000 people in the United States and Sweden, researchers found that genetic predispositions for traits like cognitive performance and subjective well-being were linked to higher voter turnout, and comparisons between siblings suggested that some of these links reflect causal genetic effects.
Political scientists typically focus on environmental factors, such as education, income, or family upbringing, to explain why some people vote and others stay home. Over the past 15 years, however, twin, adoption, and molecular genetic studies have indicated that political orientation and civic participation are also partly heritable. Integrating these findings into mainstream political science has been difficult, in part because early attempts to link political behavior to a handful of specific genes largely stalled as it became evident that complex traits are shaped by thousands of genetic variants with tiny effects.
To overcome these limitations, a research team set out to introduce a new tool to the study of political behavior. The team included Rafael Ahlskog and Sven Oskarsson of Uppsala University, Christopher Dawes of New York University, and Aaron Weinschenk of the University of Wisconsin-Green Bay. They proposed using polygenic indices, which are individual-level scores that summarize a person’s genetic propensity for a specific trait.
A polygenic index is created by looking at hundreds of thousands of tiny variations in a person’s DNA. Researchers assign a weight to each variation based on how strongly it correlates with a given trait in massive genome-wide association studies. These underlying studies analyze the DNA of very large samples, sometimes more than a million people, to find tiny statistical links between specific genetic markers and specific outcomes. By adding all these weighted variations together, researchers can generate a single score that estimates an individual’s genetic likelihood of exhibiting traits like extraversion, depression, or high cognitive performance.
To demonstrate the method, the researchers analyzed data from four large samples: the National Longitudinal Study of Adolescent to Adult Health, the Wisconsin Longitudinal Study, and the Minnesota Twin Family Study in the United States, and the Swedish Twin Registry. The combined datasets included more than 50,000 individuals, and the analyses were limited to people of European ancestry. The researchers gathered information on self-reported voter turnout, turnout validated from official records in both high-profile elections (such as presidential or national parliamentary elections) and lower-profile ones (such as U.S. midterms and European Parliament elections), and engagement in non-voting political activities, such as attending a political rally or contacting a politician.
Alongside the political data, the researchers calculated polygenic indices for ten health and psychological traits. These traits included cognitive performance, adventurousness, extraversion, being a morning person, neuroticism, risk tolerance, self-rated health, depression, subjective well-being, and physical activity. They also included a genetic score for educational attainment as a benchmark for comparison, and the main analyses followed plans the researchers had registered in advance.
The researchers first compared people across different families. To account for broad genetic differences that arise from human demographic history rather than specific traits, they controlled for participants’ genetic ancestry, along with birth year and sex.
Several genetic scores were associated with voter turnout. Higher genetic propensities for cognitive performance, self-rated health, subjective well-being, and physical activity predicted a higher likelihood of voting, while scores for neuroticism and depression predicted lower turnout. A genetic tendency toward being a morning person was associated with higher turnout in high-profile elections, and the score for adventurousness with higher turnout in lower-profile ones. Results for risk tolerance were mixed, with higher scores linked to lower turnout in high-profile elections but higher turnout in lower-profile ones.
The associations were modest but not trivial. A one standard deviation increase in the genetic score for cognitive performance or self-rated health was associated with a roughly 4 percentage point higher likelihood of voting in lower-profile elections, and each of these scores accounted for almost 1% of the variation in turnout in those elections.
When looking at non-voting political participation, the researchers found a different pattern. Genetic scores for extraversion, risk tolerance, and adventurousness were positively associated with activities like contacting a politician or attending rallies. This aligns with previous research suggesting that outgoing and novelty-seeking people are drawn to the more social aspects of political activism.
Additional analyses suggested that, on average, about 30% of the scores’ links with participation ran through the traits they were designed to predict. This varied widely: measured cognitive performance accounted for almost all of the link between its genetic score and participation, while measured physical activity explained very little of its score’s link.
While comparing people across families reveals an association, it does not prove a direct causal link. The study authors point to two main sources of bias in such comparisons: population structure and genetic nurture. Population structure refers to genetic differences that align with social or cultural groups due to historical mating patterns, which can create false correlations. Genetic nurture occurs when parents’ genes influence the environment they create for their children, meaning a child’s behavior might be shaped by their upbringing rather than their own DNA.
To establish a firmer causal connection, the researchers conducted a second set of analyses that restricted the data to pairs of full siblings. Because biological siblings receive a random mix of their parents’ genes, any genetic differences between them are the result of chance. Comparing siblings to each other effectively removes the influence of their shared family environment and broad population-level genetic differences.
In the sibling analyses, many of the links between the genetic scores and voter turnout held up, particularly for high-profile elections. For lower-profile elections, the estimates comparing siblings tended to be smaller than those comparing different families, suggesting that the earlier results were partly inflated by genetic nurture or population structure. Results for self-reported voting and non-voting participation were less precise.
Because genetic differences between siblings arise by chance, the authors argue that the within-family results can be given a causal interpretation: the genetic variants captured by these scores affect the likelihood of voting. That does not necessarily mean they work through the traits the scores were designed to measure.
The authors note several limitations to how these findings should be interpreted. A genetic effect does not mean that a person’s political behavior is biologically predetermined. Genetic influences often work through environmental pathways; for example, a genetic propensity for height might affect political participation because of wage discrimination against shorter people, rather than through any direct biological drive to vote.
Genes frequently affect multiple traits at the same time, a concept known as pleiotropy. A genetic score designed to predict depression might also capture genes related to entirely different characteristics that ultimately influence political behavior. The scores also capture only a fraction of the total genetic influence on a trait, as they are based on estimates containing some statistical noise, so the authors describe their results as a lower bound.
A major limitation of current polygenic indices is that they rely on genetic databases that predominantly feature individuals of European ancestry. Because genetic markers differ across populations, these scores are currently less accurate when applied to people of other ancestral backgrounds, which is why the analyses were limited to people of European descent.
Future research could use genetic scores to better understand how parents socialize their children politically. By comparing the genetic scores of parents and children, researchers can tease apart which political behaviors are passed down through a shared environment and which are inherited biologically.
The method also offers a way to study how different environments might amplify or suppress a person’s genetic predispositions. In one exploratory analysis that was not part of the preregistered plan, education appeared to buffer the negative link between depression-linked genes and voter turnout. The lower turnout associated with the depression genetic score appeared to be driven entirely by people at the lower end of the education distribution.
The study, “The Genetics of Political Participation: Leveraging Polygenic Indices to Advance Political Behavior Research,” was authored by Rafael Ahlskog, Christopher Dawes, Sven Oskarsson, and Aaron Weinschenk.
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