The first study showed that a genetic risk factor that increases the likelihood that youth will engage in substance use can be moderated by high levels of involved and supportive parenting

 This is an evidence showing that better parenting may suppress the negative effects of an addiction gene and decrease the risk of addiction in adolescence period:

 http://www.sciencedaily.com/releases/2009/02/090210125437.htm

 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2868377