Our findings also provide initial evidence that DHS variants are more likely (compared to non-DHS variants) to be involved in gene-by-environment interaction effects. The study of measured gene-by-environment interaction is controversial, in part owing to problems surrounding the selection of the handful of SNPs in “usual suspect” candidate genes commonly examined (Dick et al., 2015, Duncan and Keller, 2011). Our results provide evidence for an empirically based approach that builds on findings from twin studies, GWAS, and functional genomics to select SNPs for studies of measured G×E. Thus, there may be a biologically and empirically justifiable way forward to identify the variants likely to be moderated by environmental factors. Important questions remain about the specific mechanisms underlying these statistical interactions, and where in the pathway from genes to behavior an environmental factor is likely to exert its moderating effect (Moore and Thoemmes, 2016). We speculate that DHS SNPs may be especially responsive to environmental inputs given their involvement in gene regulation (Liu et al., 2008).
