Genetic and environmental contributions to prosocial behaviour in 2- to 9-year-old South Korean twins

Although over 50 twin and adoption studies have been performed on the genetic architecture of antisocial behaviour, far fewer studies have investigated prosocial behaviour, and none have done so on a non-western population. The present study examined mothers' ratings of prosocial behaviour in 514 pairs of 2- to 9-year-old South Korean monozygotic and dizygotic twins. Correlational analyses showed a tendency of increasing genetic effects and decreasing shared environmental effects with age although shared family environment effects and the moderating effects of age did not attain statistical significance in model-fitting analyses. The best-fitting model indicated that 55% (95% CI: 45-64%) of the variance in the 2- to 9-year-olds' prosocial behaviour was due to genetic factors and 45% (95% CI: 36-55%) was due to non-shared environmental factors. It is concluded that genetic and environmental influences on prosocial behaviour in young South Koreans are mostly similar to those in western samples.     

Blood group antigens and the population genetics of Macaca mulatta on Cayo Santiago. I. Genetic differentiation of social groups

The red blood cell phenotypes for eight polymorphic loci were determined for 293 free-ranging Macaca mulatta living on Cayo Santiago; this number represents the total population of the island, disposed in four social groups plus peripheral males. The rhesus population shows significant genetic heterogeneity over blood group systems (loci) and social groups. No particular genetic locus or social group is solely responsible for the genetic heterogeneity observed. The distributions of genotypes for two loci (G and H) do not deviate significantly from Hardy-Weinberg expectations within social groups or in the population as a whole. Correction of the equilibrium expectations for the effect of population subdivision yields no statistically significant results. Overall, the results suggest that the interaction of a variety of processes (random genetic drift, founder effect, migration and selection) may be responsible for the diversity observed. These data, combined with those from further studies, may allow an application of behavioral and genetic knowledge to the study of microevolutionary processes among nonhuman primates.