Daniel J. Benjamin et al. (long list)
Preferences are fundamental building blocks in all models of economic and political behavior. We study a new sample of comprehensively genotyped subjects with data on economic and political preferences and educational attainment. We use dense single nucleotide polymorphism (SNP) data to estimate the proportion of variation in these traits explained by common SNPs and to conduct genome-wide association study (GWAS) and prediction analyses. The pattern of results is consistent with ﬁndings for other complex traits. First, the estimated fraction of phenotypic variation that could, in principle, be explained by dense SNP arrays is around one-half of the narrow heritability estimated using twin and family samples. The molecular-genetic–based heritability estimates, therefore, partially corroborate evidence of signiﬁcant heritability from behavior genetic studies. Second, our analyses suggest that these traits have a polygenic architecture, with the heritable variation explained by many genes with small effects. Our results suggest that most published genetic association studies with economic and political traits are dramatically underpowered, which implies a high false discovery rate. These results convey a cautionary message for whether, how, and how soon molecular genetic data can contribute to, and potentially transform, research in social science. We propose some constructive responses to the inferential challenges posed by the small explanatory power of individual SNPs.
Reflection on these results: The idea of genetic transmission of complex social traits, like political ideology, finds new evidence in its favor, although twin studies may be giving heritability estimates that err on the high end. Or, the alternative methodology tried here may be giving estimates on the low end. But either way, it sure looks like something is being inherited that gets expressed as ideology.
However, finding a single “liberal gene” or “conservative gene” just ain’t gonna happen. The studies that we’ve heard about so far focusing on individual “political” genes may be suspect, and much larger samples will be needed. In all likelihood, there isn’t going to be any one gene that does a lot of work to explain ideology–the phenomenon is going to be polygenic…and very tough to study.
In other words, a research opportunity. Back to work, liberals!