The final cohort in our study, those born during the mid- to late 1950s through the 1960s, were socialized about smoking at a time when local, state, and federal lawmakers began to enact and enforce policies aimed to reduce cigarette consumption. When smoking is stigmatized, expensive, and banned in public places, social forces affect smoking among most persons, both with and without genetic tendencies to smoke. These social controls will causally influence the degree to which genetic characteristics differentiate between individuals. Thus, during this period, the genetic influences on smoking will decrease. This change is consistent with the social control model.
