Two twin studies investigated the moderating effect of school-level variables on heritability of adolescent smoking behavior (95,96). Findings from Daw et al. (2013) suggest that an individual’s susceptibility to school-level patterns of smoking is conditional on the number of short alleles in 5-HTTLPR. The greater the number of short alleles, the stronger the individual’s response to the school health behavioral environment (39). No interaction effects were found between dopaminergic genes and peer smoking (9). Institutional control, which incorporated measures of school smoking policies implemented by adults and whether teachers could smoke on school grounds, was not found to significantly interact with genetic influences on daily smoking among youth (95). There was also no evidence for interaction between state-level smoking by adults, measured by the percentage of adults reporting regular use in the Behavioral Risk Factor Surveillance System (1992–1993), and genetic influences on regular use during adolescence. This was not the case for state-level smoking by youth, measured by the percentage of 9th to 12th graders reporting frequent smoking, which was found to be negatively associated with genetic influences on regular
