In the case of SUDs, evidence for potential equifinality comes from at least two sources. First, a large body of research documents the salience of individual differences in understanding the etiology of alcoholism (e.g., Cox et al., 2001; Zucker et al., 2006). These differences suggest that various risk processes are differentially relevant across subgroups of individuals. For example, the extent to which alcohol serves to dampen physiological stress responses varies systematically across individuals and is greater among those with a family history of alcoholism (Sher & Walitzer, 1986; Sher, Grekin, & Gross, 2007). These findings indicate that pathways incorporating a physiological vulnerability for using alcohol to manage stress are potentially more salient for children of alcoholic parents than for their peers. A broad array of such risk and protective factors contribute to the development of substance involvement (Hawkins, Catalano, & Miller, 1992). The common finding that individual differences are important in the prediction of adolescent substance use indicates that youth vary in the etiological factors leading to SUDs and thus perhaps in their development pathways to these disorders.
