A person’s economic political views are shaped by their genetic predisposition for cognitive performance interacting with their childhood social class. People with a higher genetic likelihood for cognitive performance tend to adopt left-wing policies if they grew up poor, and right-wing policies if they grew up wealthy. The research was published in Political Psychology.
Understanding differences in economic policy preferences is a primary goal of political science. Traditional models in political economics assume that individuals will support policies that benefit them financially. In a strictly theoretical system where flat taxes are redistributed equally, anyone earning below the average income should want complete redistribution, while anyone earning above the average should oppose it. While real political systems are messier, the fundamental dynamic generally holds.
Low-income earners tend to benefit from proportional taxation and redistribution, while high-income earners bear the costs. In recent years, researchers have found that genetics also influence political behavior. Studies using various methods have documented genetic overlaps with political preferences. This overlap means that ideological preferences partially share the same genetic architecture as other measurable traits.
Since our distant ancestors did not have modern tax systems or mass political parties, evolutionary forces could not have shaped economic ideology directly. Genetic effects on these preferences must operate through intermediate traits, which scientists call endophenotypes. Some researchers proposed that cognitive performance might act as one of these intermediate traits.
The results of previous studies on cognitive performance and economic ideology, however, have been wildly inconsistent. Some studies showed a positive link between cognitive ability and economic conservatism. Other studies found a negative link, and some found no connection at all.
Rafael Ahlskog, a researcher at the Department of Government at Uppsala University in Sweden, thought these contradictory results could be reconciled. He proposed a gene-environment interaction. This occurs when a specific genetic factor behaves differently depending on the environment surrounding the individual.
Ahlskog theorized that cognitive performance does not push a person toward a specific political ideology on its own. Instead, cognitive capacity helps people analyze complicated policy packages and accurately deduce their own class interests. Modern economies feature vast arrays of diverse taxes, regulations, and benefit programs. Evaluating how these policies interact requires analytical effort.
By applying these conceptual frameworks, the study connects the theories of classical economics with modern genetics. People who find it easy to perform the mental calculations required to navigate tax proposals will optimize their policy preferences. Those who find it more difficult might answer policy questions more randomly, or they might rely on social cues not strictly tied to their personal class background.
In addition to this, political science maintains a long-standing theory regarding the impressionable years in human development. This theory states that environmental influences on attitudes are most potent during late adolescence and early adulthood. After this period, political preferences tend to stick. Based on this, Ahlskog suggested that the perception of one’s class interest is shaped primarily by the relative economic standing of their parents during these formative years.
To test these ideas, Ahlskog analyzed data from a large sample of fraternal twins from the Swedish Twin Registry born between 1943 and 1958. Fraternal twins are siblings born at the same time who share, on average, half of their genetic sequence. Using within-family differences among fraternal twins provides an excellent natural experiment for behavioral researchers.
Researchers value within-family sibling designs because comparing two people from the broader population introduces confounding variables. Between two random strangers, a genetic correlation might be skewed by regional ancestry differences or by the environmental impacts of their parents’ genes. Fraternal twins share the exact same family environment, and their genetic differences result purely from the random shuffling of DNA during conception.
Because of this randomization, systematic downstream differences in sibling behavior have a causal interpretation. Researchers can confidently conclude that the genetic difference caused the behavioral difference, rather than an unmeasured environmental factor.
To conduct the analysis, Ahlskog utilized variation in a genetic measure called a polygenic index. A polygenic index is an individual-level predictor of a specific trait that is based entirely on a person’s DNA. Geneticists build these indices by identifying thousands of tiny DNA variations known as single nucleotide polymorphisms that correlate with a target trait. The index used in this study summarized each twin’s genetic propensity for cognitive performance based on previous large-scale genomic discoveries.
He combined this genetic data with the twins’ responses to an extensive survey conducted by the Swedish Twin Registry between 2009 and 2010. The survey included a detailed battery of over thirty political preference questions. Participants rated policy proposals on a five-point scale ranging from strongly disagree to strongly agree. Ahlskog isolated twelve items specifically dealing with economic ideology, such as opinions on taxation, welfare distribution, the public sector, and government regulation.
To measure family socioeconomic standing, Ahlskog utilized Swedish registry data covering the twins’ parents. He calculated a relative affluence score by comparing the parents’ income and education levels to other adults in their specific local parishes. This provided a localized measure of class background. Sociologists have found that people typically compare their economic status to their immediate neighbors rather than the national average.
When looking at the average effect across the entire sample, the genetic measure for cognitive performance had no impact on economic conservatism. The effect size appeared as practically zero. Without looking deeper, this might seem like a simple lack of an effect.
When Ahlskog factored in the family’s socioeconomic background, the average null effect broke apart to reveal two distinct, opposing trends. Among children raised in relatively poorer families, a higher genetic index for cognitive performance caused more left-wing economic views. These individuals favored higher taxation and wealth redistribution.
Among children from affluent backgrounds, the effect reversed entirely. A higher genetic index among these privileged individuals caused more right-wing views. They favored market reliance and reduced welfare spending. The genetic factor altered how individuals optimized their political views based entirely on their childhood class.
In the scientific taxonomy of gene-environment interactions, researchers often distinguish between dimmer effects and lens effects. A dimmer effect happens when a change in the environment alters the magnitude of a genetic influence, making it stronger or weaker. A lens effect happens when the environment actually changes the direction of the genetic influence. Ahlskog’s findings represent a rare, robust example of a lens effect for a socially relevant behavior.
The researcher also controlled for the twins’ adult income and education levels. The environmental interaction held up even when accounting for later-life resources. This suggests the genetic influence operates specifically on the early-life formation of class identity, not simply on a voter’s current bank account balance.
As a placebo test to verify his theory, Ahlskog applied the same analytical models to social ideology. Social ideology involves cultural and moral issues, such as immigration, criminal justice policy, and animal rights. Unlike economic ideology, there is no direct personal financial benefit to optimizing social preferences based on household class.
In this test, he found that a higher genetic index was naturally associated with lower social conservatism across the board. The effects operated in parallel for both the rich and the poor. There was no interaction based on socioeconomic background.
The study features a few limitations and caveats. The genetic predictor is a noisy measurement that only captures a fraction of the actual heritable traits for cognitive performance. Comparing genetic differences within local twin pairs amplifies this measurement noise even further. As a result, the reported effects are likely much smaller than the actual biological impact.
The geographical and historical realities of the respondent group also matter. The individuals in this sample grew up in Sweden during the middle of the twentieth century, a period defined by the rapid expansion of the modern welfare state. Class-based politics and labor movements were highly salient in their daily lives.
The findings might look completely different in populations where economic ideology is not the primary dividing line in public debate. In political environments where left-wing economic positions are championed by socially conservative populists, the class dynamics could manifest in alternate ways. Finding out which specific political relationships are affected by changing social cultures will require further study.
Ultimately, the findings demonstrate that genetic influences on political behavior are highly contingent on social environments. An effect that appears to be mathematically zero on average can obscure shifting dynamics beneath the surface. This heavy dependency on outside environmental factors functions as a strong argument against genetic determinism.
The study, “Class, genes, and rationality: A gene-environment interaction approach to ideology,” was authored by Rafael Ahlskog.
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