Bullying Behavior May Be Genetic

A Study in Twins Finds

The type of aggressive antisocial behavior seen in bullies is more likely to be inherited than are nonaggressive antisocial behaviors such as delinquency, truancy and theft, according to a study conducted in Sweden and Great Britain.

The study examined antisocial behavior in a group of 1,500 pairs of Swedish and British twins. A third of the Swedish pairs and half of the British pairs were identical twins, sharing all of the same genes. The rest were fraternal twins, sharing about half of their genes.

The identical twins were more likely than fraternal twins to share a tendency toward aggressive antisocial behavior, indicating a role for genes in the behavior. The findings for nonaggressive antisocial behavior differed for boys and girls. Interestingly, for boys, identical twins were just as likely as fraternal twins to share symptoms of nonaggressive antisocial behavior--indicating they learn it from their environment rather than inherit it. In contrast, girls' behavior appears to stem more from their genes, the study found.

Children's peers also play a large influential role in boys' and girls' behavior, the study found. And that influence may be quite different for each member of a twin pair.

The study was conducted by Thalia Eley, PhD, of the Institute of Psychiatry in London, Jim Stevenson, PhD, of the University of Southampton, and Paul Lichtenstein, PhD, of the Karolinska Institute in Sweden. It is published in Child Development (Vol. 70, No. 1, p. 155-168).