Chunk #52 — Reasons to be Concerned about the Published cGxE Literature — Problems with the Recipe: Statistical Concerns in cGxE Research — cGxE versus gene-environment correlation (rGE)
Gene-environment correlation, or rGE, refers to instances where exposure to environment is non-random and correlated with genetic vulnerability3, whether through passive, active or evocative processes4. For instance, in classical behavior genetics, rGE is represented by genetic factors that influence the outcome (e.g. alcohol and tobacco use) and the environment (e.g. peer relationships; Harden et al., 2008) as indexed by a genetic correlation. Similarly, in measured gene studies, presence of rGE is indexed by variations in genotype or allelic frequency as a function of the environmental exposure. For instance, Salvatore and colleagues report an association between a polygenic score for alcohol problems and peer deviance (Salvatore et al., 2014), indicating that individuals who are at genetic risk for alcohol problems are also more likely to have deviant peer groups. It is likely that for many outcomes both rGE and cGxE may be important; however, the presence of rGE can complicates the interpretation of cGxE. Behavioral genetic and twin models implement several statistical approaches to account for and even explicitly model rGE (e.g., L. Eaves & Erkanil, 2003; Purcell, 2002; van der
