The relationship between parents’ and their children's substance use may operate through both biological or heritable (Kendler, Karkowski, & Prescott, 1999; Schuckit, 2009) and psychosocial, mechanisms (Kerr & Stattin, 2000; Rutherford, Cacciola, Alterman, McKay, & Cook, 1997). Social learning theory suggests that parental substance use may have a modeling effect (Bandura, 1977), by which parents’ substance use behaviors encourage imitation by adolescents. Parental substance use may also impair parenting (Van der Vorst, Engels, Meeus, Dekovic, & Vermulst, 2006), which may also affect the development of adolescent substance use. However, the theory of social control suggests that in the presence of parental substance use behaviors, adolescents will be less likely to use substances themselves if they experience high levels of parental support (e.g., closeness) and control (e.g., monitoring; Hirschi, 1969).