The study found that delinquency abstainers and nonabstainers differed on a number of variables. Abstainers, both males and females, reported having less contact with drug-using peers than nonabstainers. In addition, abstainers also had higher levels of self-control. Both DRD2 and DRD4 DNA alleles (genetic factors) were significantly associated with male abstainers compared with nonabstainers; however, these genetic factors failed to reach statistical significance for females. This finding confirms previous research that suggests males and females have a different set of factors related to the presence or absence of delinquent behavior. The dopamine D2 receptor gene (DRD2) is a polymorphism that consists of two alleles (A1 and A2 alleles). Genetic research has shown that the A1 allele is a risk factor linked to a number of behavioral and psychiatric disorders. In addition, research has indicated that the seven-repeat dopamine D4 receptor gene (DRD4) is associated with the development of certain antisocial behaviors. The authors note that the social factors (self-control and lack of association with drug-using peers) may not stem only from nongenetic influences, since prior research has suggested that self-control and the disposition to associate with delinquent and nondelinquent peers may be related in some measure to genetic factors. The authors recommend that research on delinquent behavior include a multifactorial arrangement of psychological, environmental, and genetic factors, since all play a role in the level and perhaps type of delinquent behavior. Data from the National Longitudinal Study of Adolescent Health were used to determine delinquency and sociodemographic variables. A subsample of respondents (n=2,574) was genotyped for certain genetic polymorphisms related to the synthesis of neurotransmitters. 2 tables and 50 references