Abstract
Gene by Intervention (GxI) interaction studies examine how a person’s genotype may moderate (i.e., increase or decrease benefit from) an intervention’s impact, typically in the context of randomized controlled trials. This systematic review examines genetic moderation effects for psychosocial and behavioral interventions that are family-based or school-/individual-based with family components. Differential susceptibility was the most widely used theory. All studies demonstrated significant GxI effects, but the large numbers of interventions and the fragmentary information provided by different genes limits the generalizability of conclusions. Future research should develop stronger biobehavioral theories, designs, and methodologie for studying genes in the family context. The GxI effects reviewed deepen our understanding of genetic moderation effects in intervention studies, provide implications for research by indicating who may benefit more from an intervention, and further guide efforts to personalize intervention programs to include elements to which people with certain genetic characteristics are more sensitive.