Chunk #34 — I. Heritability of Aggression: Twin and Adoption Studies — E. Does heritability vary depending on study design (twins vs. adopted siblings)?
There were only a handful of studies identified examining the heritability of aggressive behavior using the sibling adoption design. Visual inspection of the results from these sibling adoption studies (see Table 8.1) compared to the results from studies including twin samples (Table 8.2) indicate that heritability estimates (i.e., h2) and the shared environmental estimates (i.e.,c2) for aggressive behavior are very similar. This is also well in line with the results of a meta-analysis on antisocial andaggressive behavior that foundnodifferences between twin and siblingadoption studies (h2 = 48%; c2 = 13%, e2 = 0.39%) (Rhee and Waldman, 2002). Thus, the heritability of aggressive behavior does not seem to vary depending on study design.
