Liberals tend to have higher IQs than their conservative siblings

A new study from an excellent team of scientists at the U. of Minnesota finds that higher IQ siblings tend to be more politically liberal than their lower IQ brothers and sisters. And polygenic scores for IQ predict liberalism even better than do IQ tests.

Since Thomas Bouchard’s famous 1990 Minnesota Twins study reuniting identical twins largely raised apart, the University of Minnesota has been a leader in hard-headed analyses of the effects of nature and nurture using sibling, twin, and adoption studies along with the new polygenic scores.

Here’s an important new article in the scientific journal Intelligence out of Minnesota’s crack psychology department:

Predicting political beliefs with polygenic scores forcognitive performance and educational attainment

Tobias Edwards, Alexandros Giannelis, Emily A. Willoughby, James J. Lee

Department of Psychology, University of Minnesota Twin Cities

Abstract

Intelligence is correlated with a range of left-wing and liberal political beliefs. This may suggest intelligence directly alters our political views. Alternatively, the association may be confounded or mediated by socioeconomic and environmental factors. We studied the effect of intelligence within a sample of over 300 biological and adoptive families, using both measured IQ and polygenic scores for cognitive performance and educational attainment. We found both IQ and polygenic scores significantly predicted all six of our political scales. Polygenic scores predicted social liberalism and lower authoritarianism, within-families. Intelligence was able to significantly predict social liberalism and lower authoritarianism, within families, even after controlling for socioeconomic variables. Our findings may provide the strongest causal inference to date of intelligence directly affecting political beliefs.

Trust me when I say that that this study isn’t some conspiracy rigged up by leftists to make conservatives look bad.

Here’s one graph from the paper, but the decision to score liberalism as a positive number means that liberal positions are on the right in the graph and conservative views on the left:

So I flipped it around so leftism is on the left:

Interestingly, “genotypic IQ” as estimated from DNA turns out to estimate the highest degree of liberalism of all the approaches.

One thing to keep in mind is that the data comes from the Sibling Interaction and Behavior Study at the Minnesota Center for Twin and Family Research. All the parents are white Minnesotans. The children are a mixture of white biological children, white adoptees, and South Koreans adoptees.