of two s alleles of DRD4 who experienced high levels of life stress did not evince increases in substance use or in either intermediate phenotype. Similarly, the present study demonstrated that G×E effects on the intermediate phenotype of protective parenting processes accounted for G×E effects on a prevention outcome. Together, these two studies have begun to identify the mechanisms through which G×E effects operate and provide information that informs the etiology of substance use and abuse.
