The converse has also been demonstrated: impulsivity as measured in prospective studies has been shown to predict the development of alcohol use disorders (e.g. Dawes, Tarter & Kirisci 1997; Clark, Vanyukov & Cornelius 2002), and to mediate the relationship between parental substance use disorders and the eventual development of substance use disorders in offspring (Tarter et al. 2004). The fact that impulsivity is elevated in offspring who are at high risk for substance use disorders based on a parental history of substance use disorders suggests that impulsivity may be a reflection of a genetic vulnerability for substance use problems. This hypothesis is further supported by twin data that indicate that a variety of different disorders that are characterized by impulsive behavior, including alcohol dependence, drug abuse/dependence, childhood conduct disorder and adult antisocial behavior overlap largely due to an underlying shared genetic liability (Kendler et al. 2003). Personality traits related to impulsivity also load on this latent genetic factor (Young et al. 2000; Krueger et al. 2002). In fact, twin studies suggest that genetic factors contributing to variation in dimensions of
