Whereas the identification of specific genetic variants is necessary to determine the underlying biological mechanism of risk, understanding how these variants interact with aspects of the environment, both on the individual and macro levels, to produce risk for smoking behaviors remains crucial to develop downstream public health interventions. Epidemiologists have long been investigating smoking and related substance-use behaviors in heterogeneous populations.19 For example, (self-identified) African Americans, on average, initiate smoking later20 and smoke fewer cigarettes per day,20, 21 yet are less likely to successfully quit smoking. Further, they have a higher risk of smoking-related lung cancer than many other populations.22 In addition, individual-level factors, such as the experience of trauma23 and lack of social support from family and peers,24 have been associated with increased substance use.25
