Scientists were able to understand why relatives argue heatedly about politics in families

In a recent study published in the journal Intelligence, researchers found that both IQ scores and genetic markers associated with intelligence can predict political leanings toward liberalism. This means that a person’s political beliefs may not only be the result of environment or upbringing, but also depend on genetic variations that influence intelligence.

Past research has linked intelligence to socially liberal beliefs and even, to a lesser extent, fiscal conservatism. However, the underlying causes of these associations remained unclear, obscured by potentially confounding factors such as socioeconomic status, education, and broad environmental influences. This ambiguity prompted the need for a more detailed investigation.

“Over the past seventy years, psychologists have reported on the correlation between intelligence and beliefs in more than a hundred publications,” explained study author Tobias Edwards. He added that despite great interest in the topic, scientists had little knowledge about why the link existed, let alone whether it might be causal.

“As the old cliché goes, correlation is not necessarily causation. I’m curious to get to the bottom of why this mysterious correlation exists,” the scientist explained.

For their study, the researchers used data from the Sibling Interaction and Behavior Project (SIBS), which previously collected extensive information on adoptive and biological families. They were recruited between 1998 and 2003 using state birth records and adoption agency data. This data set allowed the researchers to compare siblings within the same family, significantly reducing the influence of shared environmental factors and focusing attention on genetic factors.

The study included 82 biological sibling pairs, 96 adoptive sibling pairs, and an additional 35 pairs consisting of one adoptive and one biological sibling.

Intelligence assessment in this sample was carried out in two ways, including both traditional IQ tests and genetic analysis. Participants aged 16 years and older were assessed using the Wechsler Intelligence Scale-Revised for Adults (WAIS–R), while participants aged 15 years and younger were assessed using the WISC-R for Children. These assessments are among the most widely recognized and respected measures of intelligence performance.

In addition to traditional IQ tests, the researchers examined polygenic measures of cognitive ability and educational attainment. The first data is a cumulative measure of genetic predisposition to certain personality traits. They are calculated by summing the effects of numerous genetic variants across the genome.

Researchers have found that both IQ and polygenic scores are significant predictors of political orientation. This pattern persisted even when various socioeconomic factors were taken into account.

Within families, siblings with higher IQs or more favorable polygenic intelligence scores were more likely to have liberal political beliefs compared to their siblings. This was typical for both biological and adoptive families.

This result highlights the potential genetic underpinnings of political ideology, suggesting that differences in genetic factors associated with intelligence may partly explain why siblings raised in the same environment may develop different political views.

“We found that both IQ and genetic measures of intelligence, known as polygenic scores, can help predict which of two siblings tends to be liberal,” Edwards told PsyPost. “This means that intelligence is linked to political opinions not just because of environment or upbringing, but rather because genetic variations in intelligence may play a role in influencing our political disagreements.” Why is this so? I don’t know”.

The researchers assessed six different dimensions related to political ideology: authoritarianism, egalitarianism, social liberalism, fiscal conservatism, and religiosity. IQ and polygenic scores significantly predicted all six of these political dimensions.

“We find that intelligence data has a negative impact on fiscal conservatism, whereas previous studies have generally found the opposite result,” Edwards said. “Our sample consisted of Americans who were surveyed about their political views around 2017, suggesting that the relationship between intelligence and political beliefs may have changed over time.”

According to the researcher, many smart people believed in ideas that were completely stupid. Because of this, George Orwell doubted that the intelligence of partisans could in any way determine the quality of their beliefs, stating that “one must be one of the intelligentsia to believe such things: no ordinary man could be such a fool.”

However, the researchers argue that intelligence is only one of many factors that influence political beliefs and caution against drawing conclusions about the merits of political ideologies based on the intelligence of their adherents.

“Based on our research, we cannot say that the beliefs of people with high IQs tell us what is right to believe, but rather only what smart people choose to believe,” concluded Tobias Edwards.