Vol. 11, No. 3, 2005 Page 7
Callous, unemotional traits in very young children—which can be a warning sign for future psychopathy—are largely due to hereditary rather than environmental factors, according to recent research.
Essi Viding and colleagues studied same-sex twin pairs, using teachers' ratings to identify pairs in which at least one twin had high scores for callous, unemotional behavior and pairs in which at least one twin had high scores for antisocial behavior. The researchers investigated hereditary and environmental influences on each behavior, and analyzed the differences between antisocial children with and without callous, unemotional behavior. They determined the relative strength of hereditary and environmental factors by comparing identical twins to fraternal twins (who share only half as many genes).
Viding et al. say their data revealed a powerful hereditary influence on levels of callous, unemotional behavior. Moreover, they found that antisocial behavior in children with high levels of callous, unemotional behavior was "under extremely strong genetic influence and no influence of shared environment." In contrast, both environment and heredity played a role in antisocial behavior in children without callous or unemotional traits.
The researchers say that "the remarkably high heritability for callous, unemotional traits and for antisocial behavior in children with [these traits] suggests that molecular genetic research on antisocial behavior should focus on the callous-unemotional core of psychopathy."
"Evidence for substantial genetic risk for psychopathy in 7-year-olds," Essi Viding, R. James R. Blair, Terrie E. Moffitt, and Robert Plomin, Journal of Child Psychology and Psychiatry, Vol. 46, No. 6, 2005, 592-7. Address: Essi Viding, Social Genetic and Developmental Psychiatry Centre, Box Number P080, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK, spjgemc@iop.kcl.ac.uk.