From the previous sections of this manuscript, it is clear that genes and environments contribute to risk for cigarette use. However, it is important to remember that cigarette use phenotypes are complex traits arising from interactions among social-environmental, psychological, and genetic factors (93) and these interactions need to be taken into consideration when developing downstream public health interventions. Despite progress made in the prevention of and treatment for cigarette use, available treatments are effective for only a portion of smokers. Whereas the identification of specific genetic variants is necessary in determining the underlying biological mechanism of risks for cigarette-related health outcomes, understanding how these variants interact with aspects of the environment to influence cigarette use has the potential to more effectively tailor interventions to smokers’ individual risks and needs (94). In studies of gene-environment interaction, genetic effects can be modeled either as latent variables in twin and family studies or as genuine measured genes in molecular genetic studies. When genetic effects are modeled latently, the contribution of gene effects is inferred based on observed correlations between people with different degrees
