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Cosgrove-Mather, B. (2009, February 11). Study: Abuse and genetics = agression. //CBS News//. Retrieved from http://www.cbsnews.com/2100-204_162-517241.html

1. A single gene may explain why some boys -- but not all -- abused in childhood grow up to become violent or aggressive, researchers said Thursday.

2. The gene variation seems to be activated only by mistreatment in childhood, but is found in a third of the men and young boys studied,

3. 85 percent of the boys who had a weakened version of the gene and who were abused turned to criminal or antisocial behavior

4. It could also help explain why females are less prone to crime and aggression than boys are, Moffitt said.

5. "These findings may partly explain why not all victims of maltreatment grow up to victimize others."

6. If the abused boys had one version of the MAOA gene that caused their brains to produce too little of the enzyme, they were nine times more likely to become antisocial, the researchers said.

7. "Symptoms of this antisocial behavior include persistent fighting, bullying, lying, stealing and disobeying the rules during adolescence. As adults, the subjects may repeatedly violate the law, show no remorse for their actions and act impulsively and aggressively,"

8. "As adults, 85 percent of the severely maltreated children who also had the gene for low MAOA activity developed anti-social outcomes, such as violent criminal behavior," Moffitt said in a statement.

9. The abused children with normal MAOA genes were no more likely to be anti-social than those who were not abused, the study found.

10. Boys who had been maltreated but who had higher levels of MAOA were unlikely to develop behavior problems. Their version of the gene "may promote trauma resistance," Moffitt said.

11. "Its relation to aggression only emerged when we considered whether the children had been maltreated," she said. "This suggests that the best strategy for preventing violence is to prevent child abuse."

12. The gene's effects were more difficult to study in girls, because it is found on the X chromosome. Females have two X chromosomes, while males have an X and a Y. Thus, in girls, the version of the gene found in one of their X chromosomes could cancel out the effects of the other. That may help explain why females in general are less prone to violent and criminal behavior, the team said.

13. "We know that not all abused children grow up to be violent. This study supports that observation," said Sid Johnson, president of Prevent Child Abuse American.

14. Simply having that version of the gene did not guarantee a boy would grow up to be a criminal, Moffitt stressed.

15. Dr. John M. Leventhal, professor of pediatrics at Yale University School of Medicine and medical director of the child abuse program at the Yale-New Haven Children's Hospital, said the study was interesting and important because it suggests a biological factor may play a role in causing some abused children to become abusive adults.