UNC sociologists exploring the link between adolescent
delinquency and genetics have identified three genes that appear to play a
role in whether a child becomes involved in serious and violent crime.
What’s more, the impact those genes have appears to be triggered or
suppressed by social influences such as family, friends and school.
The study led by UNC sociologist Guang Guo, one of the first to link
molecular genetic variants to adolescent delinquency, sheds light on why some
individuals become serious and violent delinquents – while others with a
similar genetic makeup do not. The study, co-authored by UNC doctoral students Michael Roettger and Tianji Cai, was published in the August
issue of the American Sociological Review.
Previous behavioral studies examining gene-environment interactions have
tended to look at the relationship of genes to a single factor such as child
abuse or stress. Here, UNC researchers systematically examined several layers
of social context, such as family dynamics, peer relations and school-related
variables.
“While genetics appear to influence delinquency, social influences such as
family, friends and school seem to impact the expression of certain genetic
variants,” said Guo, a professor in the department of sociology based in the College of Arts and 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,” said Guo, who is also a faculty
fellow at the UNC Carolina Population
Center and the Carolina Center
for Genomic Sciences.
“Our research confirms that genetic effects are not deterministic,” Guo said.
“Gene expression may depend heavily on the environment.”
The three genes were the monoamine oxidase A (MAOA) gene; the dopamine
transporter 1 (DAT1) gene; and the dopamine D2 receptor (DRD2) gene. MAOA
regulates several brain neurotransmitters important in behavioral motivation,
aggression, emotion and cognition.
Among the findings, the research suggests the propensity for serious
delinquency increased dramatically among adolescent boys who both repeated a
grade and have a 2R allele version of the MAOA gene.
The study also indicates a link between the DRD2 gene and having daily family
meals. Daily meals with one or two parents are a powerful moderator for the
effect of the DRD2 gene, Guo said.
“Most delinquent and violent behaviors are considered complex,” Guo said.
“Understanding these behaviors requires understanding both their
socioeconomic-cultural components and their genetic components.”
According to Guo, the correlation of social and genetic effects on
delinquency suggests the need for the social sciences to incorporate genetic
evidence in this area of study. The findings also raise important questions
for public policy, he said.
For this study, the researchers examined a sample of approximately 1,100
males in grades 7 through 12 whose DNA and social-control measures were
available through the National Longitudinal Study of Adolescent Health. Guo
co-authored the research with Michael E. Roettger and Tianji Cai, sociology
doctoral candidates at UNC.
The research was supported in part by grants from the National Institutes of
Health and the National Science Foundation.
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