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May 28, 2005
Psychopaths are born bad, say scientists
PSYCHOPATHS are born anti-social, not corrupted by bad parenting, scientists reveal today. A study of twins showed that anti-social behaviour was strongly inherited in children with psychopathic tendencies. In children without psychopathic traits, being anti-social was chiefly the result of environmental factors. [...] The chief investigator, Dr Essi Viding, from the Medical Research Council's Social, Genetic and Developmental Psychiatry Centre at the Institute of Psychiatry, King's College, London, said: 'The discovery that psychopathic tendencies are strongly heritable suggests we need to get help for these youngsters early on.'
Reference:
Essi Viding, R. James R. Blair, Terrie E. Moffitt, Robert Plomin (2005). Evidence for substantial genetic risk for psychopathy in 7-year-olds Journal of Child Psychology and Psychiatry 46(6).
Background: Individuals with early warning signs of life-long psychopathy, callous-unemotional traits (CU) and high levels of antisocial behaviour (AB) can be identified in childhood. We report here the first twin study of high levels of psychopathic tendencies in young children.
Methods: At the end of the first school year, teachers provided ratings of CU and AB for 3687 twin pairs from the Twins Early Development Study (TEDS). For the analyses of extreme CU, we selected same-sex twin pairs where at least one twin scored 1.3 or more standard deviations above the mean on the CU scale (612 probands, 459 twin pairs). For the analysis of extreme AB, we selected same-sex twin pairs where at least one twin scored 1.3 or more standard deviations above the mean on AB scale (444 probands, 364 twin pairs). Furthermore, the extreme AB sample was divided into those who were also extreme on CU (children with psychopathic tendencies; 234 probands, 187 twin pairs) and those who did not score in the extreme for CU (children without psychopathic tendencies; 210 probands, 177 twin pairs).
Results: DeFries-Fulker extremes analysis indicated that exhibiting high levels of CU is under strong genetic influence. Furthermore, separating children with AB into those with high and low levels of CU showed striking results: AB in children with high levels of CU is under extremely strong genetic influence and no influence of shared environment, whereas AB in children with low levels of CU shows moderate genetic and shared environmental influence.
Conclusions: The remarkably high heritability for CU, and for AB children with CU, suggests that molecular genetic research on antisocial behaviour should focus on the CU core of psychopathy. Our findings also raise questions for public policy on interventions for antisocial behaviour.
Posted by Emma at May 28, 2005 09:32 AM
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