The heritability of SRE scores in ALSPAC was moderate (h2SNP=0.36) and differed significantly from 0, suggesting that aggregate genetic factors contribute substantially to initial alcohol sensitivity. However, the heritability estimates were effectively 0 for each S4S ancestry group. This pronounced difference may be due in part to assessment. ALSPAC participants were periodically assessed in the time frame during which they were likely to begin experimenting with alcohol: while 62% responded to SRE items in wave 1 (age ~15.5), the remainder had not used alcohol 5 or more times until a later assessment. In contrast, 79% of S4S participants’ reports were from wave 1 (age ~18.5) and it is likely that many were reporting on alcohol exposure several years in the past. This raises the possibility that the scores are quite sensitive to recall bias. Thus, it is unclear whether the null heritability estimates of SRE across S4S ancestry groups is due to a true absence of genetic influences on SRE in S4S, potential error introduced by retrospective reports, or other factors. We are further unable to determine whether ancestry-based differences in heritability exist.
