Sociological research shows combined impact of genetics, social factors on d...(r research confirms that genetic effects...)

The three genetic polymorphisms that predict delinquency include: (1) the 30-base pair (bp) promoter-region with a variable number tandem repeat (VNTR) in the monoamine oxidase A (MAOA) gene, (2) the 40-bp VNTR in the dopamine transporter 1 (DAT1) gene and (3) the Taq1 polymorphism in the dopamine D2 receptor (DRD2) gene. MAOA regulates several brain neurotransmitters important in behavioral motivation, aggression, emotion and cognition (e.g., serotonin, dopamine, norepinephrine).

Among the findings, the research suggests a conditional interaction between repeating a school grade and the MAOA*2 repeat (2R) allele in adolescent boys. For those who did not have the 2R allele, repeating a grade was significantly correlated with serious delinquency, but for those who had this 2R allele and who repeated a grade, the propensity for serious delinquency increased dramatically.

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.

"Most delinquent and violent behaviors are considered complex," Guo said. "Understanding these behaviors requires understanding both their socioeconomic-cultural components and their genetic components."

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, according to Guo. The implications of these findings also raise important questions for public policy.

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