https://www.sciencedirect.com/science/article/abs/pii/S0160289624000254?via%3Dihub

The original study:

https://www.sciencedirect.com/science/article/abs/pii/S0160289624000254?via%3Dihub

Main points:

Within-families, intelligence predict left-wing beliefs.


DNA-based predictors of IQ also predict political beliefs within families.


Our results imply that being genetically predisposed to be smarter causes left-wing beliefs.

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.