A series of three reports using data from the Finn Twin study has examined the role of region of residence as a moderator of genetic influences on drinking among adolescents. Heritability of drinking frequency was found to be greater in urban than rural environments, at ages 16 (34% vs. 18%), 17 (62% vs. 49%) and 18.5 (59% vs. 53%), consistent with GxE (Rose, Dick, Viken, & Kaprio, 2001). This pattern of results was replicated among 18-year-olds using more specific neighborhood characteristics, such that drinking frequency heritability was higher in municipalities with a greater percentage of young adults and more migration (Dick, Rose, Viken, Kaprio, & Koskenvuo, 2001). Neighborhood characteristics were not found to moderate genetic influences on drinking among 14-year-olds (Dick et al., 2009a), but only 34% of this younger sample had initiated drinking, limiting power to test GxE.
