Although it is plausible that important GxE interaction effects exist, few studies have been able to document the importance of such effects in the development of alcohol dependence. In an early study using twin pair data, Heath and colleagues (1989) documented an apparent interaction between genetic effects on alcohol consumption level and marital status in Australian women. In that study, the genetic influence on current alcohol consumption levels was much stronger in women with no partner than in women with a current marital or de facto partner. Similarly, Dutch researchers have identified an apparent interaction between family religious background and genetic effects on impulsive personality traits that may be associated with increased risk of alcohol dependence. This study observed much stronger genetic effects in participants reared in a more permissive religious background (Boomsma et al. 1999). Finnish researchers have documented an interaction between place of residence (i.e., urban versus rural areas) and genetic effects on drinking behavior, with genetic influences being more important in urban settings (Dick et al. 2001).
