SRE-T and SRE-5 represent self-reported assessments of LR. SRE-T and SRE-5 were moderately heritable, but our estimates were lower than some prior reports. For instance, a smaller (n=101) sibling study of non-alcohol-dependent individuals estimated the heritability of SRE-T at 67-71% (Kalu et al., 2012), although the corresponding estimate for an “early drinking period” was lower and statistically non-significant. Similar high heritability estimates have been noted for other assessments of subjective ratings (e.g., 40-60%) (Heath and Martin, 1991, Viken et al., 2003). It is possible that our estimates are less precise than those from larger twin studies, as we relied on pedigree data. We did not utilize genomic data to estimate the SNP-heritability of SRE scores as our large pedigrees, when reduced to a smaller cohort of unrelated individuals, is not well-powered to make such estimates. Nonetheless, our estimates suggest that future larger efforts should be successful in estimating the extent to which common variants explicate the heritability of SRE (Ray et al., 2010).
