Genetic and environmental bases of childhood antisocial behavior: a multi-informant twin study

Abstract

Genetic and environmental influences on childhood antisocial and aggressive behavior (ASB) during childhood were examined in 9- to 10-year-old twins, using a multi-informant approach. The sample (605 families of twins or triplets) was socioeconomically and ethnically diverse, representative of the culturally diverse urban population in Southern California. Measures of ASB included symptom counts for conduct disorder, ratings of aggression, delinquency, and psychopathic traits obtained through child self-reports, teacher, and caregiver ratings. Multivariate analysis revealed a common ASB factor across informants that was strongly heritable (heritability was .96), highlighting the importance of a broad, general measure obtained from multiple sources as a plausible construct for future investigations of specific genetic mechanisms in ASB. The best fitting multivariate model required informant-specific genetic, environmental, and rater effects for variation in observed ASB measures. The results suggest that parents, children, and teachers have only a partly "shared view" and that the additional factors that influence the "rater-specific" view of the child's antisocial behavior vary for different informants. This is the first study to demonstrate strong heritable effects on ASB in ethnically and economically diverse samples.

Figure 1

(a) Rater effects model. (b) Measurement model. (c) Full common pathways model. Observed variables are represented by rectangles; latent variables are represented by circles. A = additive genetic effects; C = shared (common) environmental influences; E = nonshared environmental influences; R = rater effects; MZ = monozygotic; DZ = dizygotic; Cgvr = caregiver; Tchr = teacher. Path coefficients with a, c, e, and r correspond to the effects of these latent factors on the observed variables. Paths marked with λ represent the factor loadings on the shared view of antisocial behavior for each individual rater. Factors and corresponding path coefficients that reflect influences on the shared view of antisocial behavior are subscripted with C. The subscripts M, K, and T refer to factors and corresponding path coefficients that are specific to the caregiver (M), child (K), and teacher (T) reports, respectively. All latent A, C, E, and R factors have an assumed variance of 1.0; the variance in the factor representing the shared view has likewise been constrained to unity.

Figure 2

Standardized parameter estimates from full common pathways model. Paths marked with an asterisk are significantly different from zero. A = additive genetic effects; C = shared (common) environmental influences; E = nonshared environmental influences; R = rater effects. Factors influencing the underlying latent shared view of antisocial behavior are subscripted with C. The subscripts M, K, and T refer to factors that are specific to the caregiver (M), child (K), and teacher (T) reports, respectively. For Caregiver Report, rater effects (R_M) and shared environmental effects (C_M) cannot be statistically differentiated in this design. Thus, these influences are noted as a single path coefficient that may reflect either or both effects on variation in caregiver reports. All latent A, C, E, and R factors have an assumed variance of 1.0; the variance in the factor representing the shared view was likewise constrained to unity.