Genes play a strong role in determining the fate of children growing up in poverty, according to a new study of twins.
Julia Kim-Cohen and colleagues studied 1,116 mothers and their five-year-old same-sex twins, all participating in a long- term study of environmental and genetic effects on behavior. The researchers analyzed the economic situation of each family, as well as each mother's level of warmth and supportiveness. To determine the effects of genes and environment, they compared monozygotic twins (who are virtually identical genetically) to dizygotic twins, who share only half their genes.
Their data, the researchers report, show that 70 percent of the variability in the children's "behavioral resilience"—that is, their ability to overcome the effects of poverty—could be attributed to genetic influences. In addition, 46 percent of the variance in cognitive ability could be attributed to genetic factors. Environment played a key role, too, with mothers who provided their children with more stimulating environments being more likely to have children with higher IQs.
The researchers conclude, "[Our] findings add new information by demonstrating that resilience is partly heritable and that protective processes operate through both genetic and environmental effects."
"Genetic and environmental processes in young children's resilience and vulnerability to socioeconomic deprivation," Julia Kim-Cohen, Terrie E. Moffitt, Avshalom Caspi, and Alan Taylor, Child Development, Vol. 75, No. 3, May 2004, 651-68. Address: Julia Kim-Cohen, Julia.email@example.com, or Terrie Moffitt at firstname.lastname@example.org.