Genes May Govern Risky Behavior in Girls

By Adam Marcus, HealthDay Reporter

HealthDayNews — When it comes to experimenting with tobacco, drugs, and alcohol, boys respond more to peer pressure while girls get the urge from their genes.

That’s the conclusion of a new study of twins that finds that the motivation for risky behavior like taking drugs and drinking are different for the sexes.

For girls, genes that predispose people to “conduct problems” — which range from defiance and rebelliousness to more serious behaviors like arson and cruelty to animals — seem to work in tandem with genes that influence a willingness to drink and take drugs, the study contends.

“There’s a common set of genes influencing both traits,” says Judy Silberg, a psychologist at Virginia Commonwealth University and leader of the research. “It could be that one triggers the others, or one gets expressed in a certain environment.”

Silberg stresses that the study results are preliminary and must be replicated. If the work holds up, she adds, it could help counselors better treat teens for drug and alcohol problems.

“You may be targeting girls as individuals while boys would be seen more as part of” an environment that needs changing, she says. For girls, the emphasis would be on tackling delinquency and other conduct problems.

Silberg and her colleagues report their findings in the July issue of the Journal of Child Psychology and Psychiatry and Allied Disciplines.

The study addressed what’s considered normal experimentation with substances, not abuse. The research — part of an ongoing look at youth behavior in Virginia — followed 1,071 twins ages 12 to 17. Most were identical, meaning they share 100 percent of the same genes, compared with only 50 percent for non-identical twins.

No one factor explained why girls and boys experimented with drugs, smoking, or alcohol, the researchers say, and genetics and environment played a role for each sex. However, Silberg says, the impact of genes was stronger on girls than on boys.

For boys “there are genetic effects [on risky behaviors] but they’re not as pronounced as they are for girls and they’re not as tied up genetically with conduct problems,” she says.

Girls who spent time with much older boys were more likely to take up the dangerous behaviors, Silberg says. This suggests the boys were introducing the girls to drugs and alcohol, she says.

Dr. Howard Moss is a psychiatrist at the University of Pennsylvania who studies the genetics of behavior. “What we may be talking about are the influences of hundreds and perhaps thousands of genes,” he says. “So it’s important to realize that we’re not necessarily talking about a gene for affiliation with delinquent boys or using marijuana. We’re talking about the summation of many genes.”

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On the Net:

National Institute on Drug Abuse

Partnership for a Drug-Free America

Virginia Commonwealth University

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