Sociopolitical conservatism is extraordinarily heritable (74%) for the most informed fifth of the public, much more so than population-level results (57%), or 29% for the public’s bottom half

Kalmoe, N., & Johnson, M. (2021). Genes, Ideology, and Sophistication. Journal of Experimental Political Science, 1-12, Mar 2021. doi:10.1017/XPS.2021.4

Rolf Degen's take: https://twitter.com/DegenRolf/status/1369339571469684738

Abstract: Twin studies function as natural experiments that reveal political ideology’s substantial genetic roots, but how does that comport with research showing a largely nonideological public? This study integrates two important literatures and tests whether political sophistication – itself heritable – provides an “enriched environment” for genetic predispositions to actualize in political attitudes. Estimates from the Minnesota Twin Study show that sociopolitical conservatism is extraordinarily heritable (74%) for the most informed fifth of the public – much more so than population-level results (57%) – but with much lower heritability (29%) for the public’s bottom half. This heterogeneity is clearest in the Wilson–Patterson (W-P) index, with similar patterns for individual index items, an ideological constraint measure, and ideological identification. The results resolve tensions between two key fields by showing that political knowledge facilitates the expression of genetic predispositions in mass politics.

Discussion

We set out to test whether political knowledge provides an “enriched environment” for genetic expression in ideology, as research on mass belief systems suggests it might do. Our approach leveraged the natural experiment derived by comparing identical and fraternal twin pairs (same-sex, raised together), a method common in behavioral genetics. The results handsomely supported our expectations: High-knowledge twin pairs show extraordinarily high heritability across varieties of ideology, while the least knowledgeable half showed more meager genetic influence, with robust results across alternative specifications. We conclude that genetic predispositions toward ideological beliefs are highly contingent (though not wholly dependent) on political knowledge for their actualization, because knowledge provides ideal conditions for making those connections.

How well does this sample reflect the national population on traits linked to ideology and knowledge? Minnesota Twin Study respondents are older and more educated than the American public, on average, but they are similarly interested in politics and unconstrained in attitudes, like national samples (Arceneaux, Johnson, and Maes Reference Arceneaux, Johnson and Maes2012). Crucially, we found that sample knowledge levels are proportionate to general population surveys. That makes these tests a reasonable basis for inferring general population dynamics on ideological heritability and political sophistication.

More broadly, we recognize our tests as the first look and not the last word. In particular, the small Minnesota samples prevent more precise subsample tests, and public access is limited for data enabling further tests. We look forward to future studies replicating and extending our results.

Philip Converse (Reference Converse2000) always said that ideological analysis must account for huge variance in the public’s political knowledge – and that doing otherwise risked concealing more than it revealed. The tests here show the value of extending Converse’s exhortation to estimates of genetic influence in belief systems. Low-knowledge citizens may inherit genetic ideological predispositions like their high-knowledge peers, but those orientations are weak without the knowledge necessary to determine concrete attitudes and broader structures. Political knowledge is a key binding element for that political development. Merging two important and related but isolated fields in this way adds insight into the origins of ideology and the conditions for genetic influence in politics.