Genetic variations help explain the link between cognitive ability and liberalism
by Eric W. Dolan
April 10, 2024
in Cognitive Science, Political Psychology
(Photo credit: OpenAI's DALL·E)
In recent research published in the journal Intelligence, scientists have found that both IQ scores and genetic markers associated with intelligence can predict political inclinations towards liberalism and lower authoritarianism. This suggests that our political beliefs may not be solely a product of our environment or upbringing but could also be influenced by the genetic variations that affect our intelligence.
Prior investigations have consistently associated intelligence with socially liberal beliefs and even fiscal conservatism to a lesser extent. However, the root causes of these associations remained ambiguous, obscured by potential confounding factors like socioeconomic status, education, and the broad influence of an individual’s environment. This ambiguity sparked a need for a more detailed investigation.
“For the last seventy years, psychologists have reported correlations between intelligence and beliefs in over one hundred publications,” explained study author Tobias Edwards, a PhD student studying behavioral genetics at the University of Minnesota, Twin Cities.
“Despite much interest in the topic, we have had little knowledge of why this link exists, let alone whether it may be causal. As the old cliché goes; correlation is not necessarily causation. I am curious to get to the bottom of why this mysterious correlation exists.”
For their study, the researchers harnessed data from the Sibling Interaction and Behavior Study (SIBS), a project that had previously gathered extensive information on adoptive and biological families. The families were recruited between 1998 and 2003, utilizing state birth records and adoption agency data. This dataset allowed the researchers to compare siblings within the same family, significantly reducing the impact of shared environmental factors and focusing on genetic influences.
The study included 82 pairs of biological siblings, 96 pairs of adopted siblings, and an additional 35 pairs consisting of one adopted and one biological sibling.
Assessment of intelligence within this sample was twofold, incorporating both traditional IQ tests and genetic analysis. Participants aged 16 years and older were assessed using the Wechsler Adult Intelligence Scale–Revised (WAIS-R), while those 15 years and younger were evaluated with the Wechsler Intelligence Scale for Children–Revised (WISC-R). These assessments are among the most widely recognized and respected measures of intelligence.
In addition to the traditional IQ tests, the researchers examined polygenic scores for cognitive performance and educational attainment. Polygenic scores represent an aggregate measure of genetic predisposition to certain traits. They are calculated by summing the effects of numerous genetic variants across the genome, each contributing a small amount to the trait of interest.
The researchers found that both IQ scores and polygenic scores were significant predictors of political orientation. This pattern held true even when controlling for various socioeconomic factors.
Within families, a sibling with a higher IQ or more favorable polygenic scores for intelligence was more likely to lean towards liberal political beliefs compared to their sibling. This was consistent across both biological and adoptive families.
This outcome underscores the potential genetic underpinnings of political ideology, suggesting that the variation in genetic factors related to intelligence could partially explain why siblings raised in the same environment might develop diverging political views.
“We find both IQ and genetic indicators of intelligence, known as polygenic scores, can help predict which of two siblings tends to be more liberal,” Edwards told PsyPost. “These are siblings with the same upbringing, who are raised under the same roof. This implies that intelligence is associated with political beliefs, not solely because of environment or upbringing, but rather that the genetic variation for intelligence may play a part in influencing our political differences. Why is this the case? I do not know.”
The researchers assessed six different facets related to political ideology: authoritarianism, egalitarianism, social liberalism, fiscal conservatism, and religiousness. Both IQ and polygenic scores significantly predicted all six of these political facets.
“We found intelligence to negatively predict fiscal conservatism, whilst past research has typically found the opposite result,” Edwards said. “Our sample consisted of Americans, questioned on their political views around 2017, suggesting that the relationship between intelligence and political beliefs may have changed over time.”
“This surprise highlights an important point; there is no law saying that intelligent people must always be supportive of particular beliefs or ideologies. The way our intelligence affects our beliefs is likely dependent upon our environment and culture. Looking back across history, we can see intelligent individuals have been attracted to all sorts of different and often contradictory ideas.”
“Intellectuals have flirted with and been seduced by dangerous ideologies and tyrannical regimes,” Edwards noted. “Many smart people have believed ideas that are downright stupid. Because of this George Orwell doubted that the intelligence of partisans could be any guide to the quality of their beliefs, declaring that, ‘one has to belong to the intelligentsia to believe things like that: no ordinary man could be such a fool.'”
As with any study, there are some limitations to consider, such as the potential for genetic confounding. “Our polygenic scores for cognitive performance (intelligence) and educational attainment are derived from genome-wide association studies (GWAS) that estimate correlations between genetic variants (SNPs) and the traits of intelligence and education,” Edwards explained.
“Some of these correlated genetic variants may not be causes of intelligence. Although siblings with higher polygenic scores do tend to be more liberal, the genetic variants may affect political beliefs through pathways other than intelligence. Future work should revisit our findings once improvements are made to GWAS methodology.”
The findings shed new light on the relationship between intelligence and political attitudes. However, the researchers emphasize that intelligence is just one factor among many that influence political beliefs and caution against drawing implications on the merit of political ideologies based on the intelligence of their adherents.
“It is very tempting to make inferences to the veracity of an ideology based on the intelligence of its supporters,” Edwards said. “But this would be a mistake. There have been extraordinarily intelligent people on both the left and right, from Oppenheimer to von Neumann. These and many more examples show that there is no reason why we must presume one ideology to be more intelligent than another, even if smart people seem more likely to align with one belief or another.”
“From our study we cannot say that the beliefs of high IQ people tell us what is right to believe, but rather only what smart people choose to believe.”
“In the past, people, both clever and dull, have been fiercely divided about political issues that seem ludicrous today, such as the divine right of kings, or the correct dress of the clergy,” Edwards added. “This hindsight of history should humble us into being less righteous in our beliefs and teach us to be tolerant of those we disagree with, regardless of their intelligence or any other psychological trait that predisposes them to particular views.”
The study, “Predicting political beliefs with polygenic scores for cognitive performance and educational attainment,” was authored by Tobias Edwards, Alexandros Giannelis, Emily A. Willoughby, and James J. Lee.
