Chunk #59 — II. G × E Interaction in Aggressive Behavior — A. Potential moderators of genetic influence found in adoption and twin studies — 1. Family adversity and social disadvantage
criminal; if only environmental factors were present, 6.7% were criminal; and with neither inherited nor environmental factors being present, 2.7% were criminal (Cloninger et al., 1982). The fact that 12.1% plus 6.7% is less than 40% would thus be an indication of G × E interactions. This finding was later replicated in females (Cloninger and Gottesman, 1987). It should be pointed out, however, that in the adoption design, the genetic risk factors themselves are considered in a general way, such that the exact nature of the genes is left unspecified, both in terms of which loci or alleles may be involved and what underlying mechanisms may be involved in the path from genes to phenotype. Similarly, the environmental risk factors as indexed by certain traits in the adoptive parents or characteristics of their home do not necessarily specify the exact nature of the child's experiences or how these lead to various outcomes.
