In the present study, we found that parental drinking (gauged by the parental combined alcohol problem index) was related to the strength of the effect of ALDH2 genotype upon both the drinking index, and the alcohol abuse and dependence symptom count, such that the protective effect of ALDH2*2 was stronger when parental drinking was lower, and weaker when parental drinking was higher (table 5). This finding is in accord with the previous observation that ALDH2*2 apparently afforded reduced protection against alcohol dependence as environmental exposure to alcohol use increased (Higuchi et al., 1994)—although in our sample, parental moderation of ALDH2 genotype effect did not extend to diagnosis of alcohol abuse and dependence per se.
