Table 2.

Key findings from studies of G–E relationships by environmental feature and level

Feature	Social Network Level
Parental alcoholism	Interaction between parental alcohol problems and protective genetic variant against drinking in Asians observed in some studies (Bujarski et al.34; Irons et al.35). Additive and interactive G–E relationships for parental alcoholism may be different across gender and population groups (Vaske et al.43).
Parenting skills intervention status	Genetic variants were associated with differential responsiveness to interventions targeting more communicative and involved parenting for African American youth (Brody et al.27–30; Beach et al.26).
Sibling alcohol use	Sibling alcohol use was a significant predictor of reduced ALDH2*2 protection against drinking (Irons et al.35,36), but non-significant findings were encountered when examining phenotypes for AUD35.
Marital status	Evidence of both G–E correlation and interaction effect in Dick et al.46, but no G–E relationships in Du & Wan39.
Peer alcohol use	Reduced protective ADH1B effect when reporting that most or all peers drink in African and European American adolescents (Olfson et al.44). ALDH2 was not correlated with peer deviance; more consistent evidence for a G–E additive relationship with alcohol-related phenotypes (Irons et al.35).
Childhood maltreatment	Evidence for an interaction between childhood abuse and genetic risk by some (MAOA, Ducci et al.41; SLC6A4, Kaufman et al.47), but not all studies (GABRA2, Enoch et al.31). GABRA2 did not correlate with childhood trauma.
Social Network & Community Level*
Adverse life events	Mixed support for joint effects between genes and adverse life events based on genetic variant, gender, and race/ethnicity, respectively, demonstrating a moderating effect for CRHBP (Goyal et al.32), African American females (Kranzler et al.33), and European American males (Sartor et al.21) only. Early life trauma, but not past-year trauma or stress, interacted with FKBP5 on heavy drinking in college students (Lieberman et al.49).
Community Level
Religious involvement	Evidence of reduced genetic risk for drinking with greater religious services attendance (Chartier et al.45; Luczak et al.37)
Social drinking norm indexes	Higher school-level alcohol use interacted with SLC6A4 genotype to predict greater alcohol consumption (Daw et al.48). Acculturation predicted more drinking with no interactive effect (Bujarski et al.34). Studies of ethnicity, gender, and educational level reported mixed additive (Luczak et al.57) and interactive (Du & Wan39; Enoch et al.40) effects as well as no G–E relationships (Hendershot et al.38).

Notes: G–E = gene-environment;

^*adverse life events were classified as social network and community level exposures due to the items included in the composite variable; and none of the studies reviewed examined environmental features at the societal level.