Essays on Genetics and the Social Sciences

This thesis explores questions at the intersection of economics and biology, and thus contributes to an emerging field of research commonly referred to as: genoeconomics, social-science genetics, biosocial science and biological economics.

Evidence from behavior-genetic studies of twins, adoptees and other pairs of relatives shows that virtually all human traits, including economic preferences and behaviors are at least moderately heritable. With more and more genetic data becoming available, it is increasingly becoming feasible to identify specific genetic variants associated with complex outcomes, thus blurring the disciplinary boundaries between the biological and social sciences. The research described here identifies specific genetic variants robustly associated with a suite of complex outcomes – ranging from educational attainment, to subjective well-being, neuroticism and depression – and shows how these findings can be used, in conjunction with quasi-experimental research designs from economics, to conduct rigorous and well-powered investigations of the interactions between genes and environment. It illustrates some hard-won lessons about the relative merits of various research strategies that have been proposed for efforts to discover genetic associations with complex traits. Furthermore, it provides a framework for quantifying trade-offs between outcome measure heterogeneity and sample-size in gene-discovery efforts.

Though considerable uncertainty remains about the ultimate value of genetic data in the social sciences, the results reported here strongly suggest that there will be at least some settings in which genetic data will prove valuable. As more genetic data become available, the number of identified associations in genome-wide association studies of complex behavioral is likely to continue to grow. In addition to broadening our knowledge about the biological mechanisms underlying behavioral outcomes, these advances will provide researchers from many disciplines with increasingly powerful tools that can be used to understand, for example, the interplay between genes and environment.