E correlation occurs when an individual’s genotype provides different reactions from the environment. Small values for c2 influences of common environments shared by members of sibpairs appear to provide evidence against “passive” G × E correlations. On these bases, “active” and “reactive” G × E correlations remain of theoretical interest. However, one influential train of thought [88, 90] suggests that G × E correlations are best regarded as parts of the genetic variance because “… the non-random aspects of the environment are… consequence(s) of the genotype(es)…”.
