Another distinction between this and prior studies of the interplay between genetic risk and peer influence is this study’s focus on the transition between significant cigarette smoking exposure and becoming nicotine dependent by virtue of the case and control criteria: current smokers with an FTND score ≥ 4 versus having smoked at least 100 cigarettes but a lifetime FTND = 0. Because all study subjects have passed the threshold of smoking initiation the effect of peer smoking in this study represents that component of peer influence that has to do with maintenance of smoking: factors such as reinforcement of pro-smoking norms or connectedness to social networks encourage adoption of a smoker social identity rather than providing opportunities to initiate smoking or models of “how” to smoke. Thus our findings suggest that given exposure to 100 cigarettes or more those with the AA genotype at rs16969968 are only minimally influenced by peers as they transition into nicotine dependence.
