Theory and research suggest that individuals shape their social environments through gene-environment correlation (rGE) processes (Plomin et al., 1977; Scarr & McCartney, 1983). Prior evidence suggests that social support is genetically influenced: some studies found that between 40% and 80% of the variance in dimensions of social support can be attributed to genetic differences between individuals (Bergeman et al., 1990; Kendler, 1997; Wang et al., 2017). Others found moderate degree of heritability for social support from spouse and parents (ranged from 15% to 30%) but small to none genetic influence on social support from friends (Kutschke et al., 2018). Twin research also showed overlap in genetic influences between social support and AUD (Salvatore et al., 2015). Taken together, it is plausible that rGE processes related to social support may serve as a pathway linking genetic factors to alcohol use outcomes. That is, higher genetic risk may lead to lower social support, which in turn can result in elevated risk for alcohol use and related problems, although the effects may vary across sources of social support.
