Does genetic makeup help determine whether someone becomes a juvenile delinquent?

Apparently so, say researchers at UNC Chapel Hill.

in delinquency, with their impact either being triggered or “suppressed” by other social influences, such as family, friends and school, the study found.

The UNC team, which called the study “one of the first to link molecular genetic variants to adolescent delinquency,” set out to explore “several layers of social context” and possible links to genetics.

"While genetics appear to influence delinquency, social influences such as family, friends and school seem to impact the expression of certain genetic variants," said Guang Guo, the study’s lead author. Guo is a professor of sociology in the UNC College of Arts and Sciences and a faculty fellow at the Carolina Center for Genomic Sciences.

"Positive social influences appear to reduce the delinquency-increasing effect of a genetic variant, whereas the effect of these genetic variants is amplified in the absence of social controls," he added. "Our research confirms that genetic effects are not deterministic. Gene expression may depend heavily on the environment."

Researchers studied 1,100 males in grades seven through 12. DNA and social control measures for the study subjects were accessible through a national adolescent health study.

Among the genes identified was monoamine oxidase A, or MAOA, which regulates several brain neurotransmitters linked to behavior motivation, aggression, emotion and cognition.

Serious delinquency “increased dramatically” among the study subjects who repeated a grade of school and had a specific version of the MAOA gene, the study reported.

Whether a subject participated in daily meals with one or two parents also served as a “powerful moderator” of another gene, the researchers said.

Grants from the National Institutes of Health and the National Science Foundation helped fund the study.