Guo and colleagues (2010) examined how the dopamine transporter gene (DAT1) interacts with age (or life course stage) in relation to risk behavior (including delinquency, number of sex partners, substance use, and seatbelt use) from adolescence into young adulthood, using data on the siblings pairs from Waves I, II and III of Add Health. They reported a protective effect of the 9R/9R genotype in the VNTR of DAT1 on risky behavior; individuals with DAT1*9R/9R compared to DAT1*Any10R, reported lower levels of risky behaviors. However, this protective effect varied according to age/life course stage, such that genetic protection is evident when the risk behavior is illegal (e.g., alcohol use and smoking in adolescence), but vanishes when the behaviors are legal or more socially tolerated (e.g., alcohol use and smoking in adulthood). This research is important because it demonstrates how legal, as well as social, contexts can enhance or diminish genetic associations with a spectrum of risky behaviors.
