It Matters What and Where We Measure: Education and Ideology in a Swedish Twin Design

Abstract Research on the link between education and political ideology is likely affected by biases common in conventional observational methods. A study by Rasmussen et al. (2021) addresses this problem by examining social and economic ideology in a Danish discordant twin design, finding that education shows positive causal effects on economic, but not social, conservatism. In this paper, I provide a set of replications of these results using a dataset of genotyped Swedish twins. I complement this by using random variation within fraternal twin pairs in a polygenic index of education. Results differ markedly from the original study, but are also shown to be sensitive to precise definitions of the ideological dimensions and which sub-dimensions or items are included. Overall, more care may be warranted when empirically defining ideology. Additionally, educational effects on ideology are likely to be sensitive to particular characteristics of the educational experience across time and space.