This study, drawing on approximately 1,100 males from the National Longitudinal Study of Adolescent Health, demonstrates the importance of genetics, and genetic-environmental interactions, for understanding adolescent delinquency and violence. Our analyses show that three genetic polymorphisms—specifically, the 30-bp promoter-region variable number tandem repeat (VNTR) in MAOA, the 40-bp VNTR in DAT1, and the Taq1 polymorphism in DRD2—are significant predictors of serious and violent delinquency when added to a social-control model of delinquency. Importantly, findings also show that the genetic effects of DRD2 and MAOA are conditional and interact with family processes, school processes, and friendship networks. These results, which are among the first that link molecular genetic variants to delinquency, significantly expand our understanding of delinquent and violent behavior, and they highlight the need to simultaneously consider their social and genetic origins.

As far as we know, this is the first national study that reports compelling evidence for the main effects of genetic variants on serious and violent delinquency among adolescents and young adults. This study investigated the association between the self-reported serious and violent delinquency and the TaqI polymorphism in the DRD2 gene and the 40-bp VNTR in the DAT1 gene. The study was based on a cohort of more than 2,500 adolescents and young adults in the National Longitudinal Study of Adolescent Health in the United States. The trajectories of serious delinquency for the DAT1*10R/10R and DAT1*10R/9R genotypes are about twice as high as that for the DAT1*9R/9R genotype (LR test, P = 0.018, 2 df). For DRD2, the trajectory of serious delinquency for the heterozygotes (A1/A2) is about 20% higher than the A2/A2 genotype and about twice as high as the A1/A1 genotype, a phenomenon sometimes described as heterosis (LR test, P = 0.005, 2 df). The findings on violent delinquency closely resemble those on serious delinquency. The trajectories of violent delinquency for the DAT1*10R/9R and DAT1*10R/10R genotype are again about twice as high as that for DAT1*9R/9R (LR test, P = 0.021, 2 df). The two homozygotes of DRD2*A1/A1 and DRD2*A2/A2 scored lower (LR test, P = 0.0016, 2 df) than the heterozygotes. The findings in the models that consider DAT1 and DRD2 jointly (serious delinquency P = 0.0016, 4 df; violent delinquency P = 0.0006, 4 df) are essentially the same as those in the single-gene models, suggesting the absence of a significant correlation between the two genetic variants. These results only apply to males. Neither variant is associated with delinquency among females.

The transition to parenthood is a stressful period for most parents as individuals and as couples, with variability in parent mental health and couple relationship functioning linked to children's long-term emotional, mental health, and academic outcomes. Few couple-focused prevention programs targeting this period have been shown to be effective. The purpose of this study was to test the short-term efficacy of a brief, universal, transition-to-parenthood intervention (Family Foundations) and report the results of this randomized trial at 10 months postpartum. This was a randomized controlled trial; 399 couples expecting their first child were randomly assigned to intervention or control conditions after pretest. Intervention couples received a manualized nine-session (five prenatal and four postnatal classes) psychoeducational program delivered in small groups. Intent-to-treat analyses indicated that intervention couples demonstrated better posttest levels than control couples on more than two thirds of measures of coparenting, parent mental health, parenting, child adjustment, and family violence. Program effects on family violence were particularly large. Of eight outcome variables that did not demonstrate main effects, seven showed moderated intervention impact; such that, intervention couples at higher levels of risk during pregnancy showed better outcomes than control couples at similar levels of risk. These findings replicate a prior smaller study of Family Foundations, indicating that the Family Foundations approach to supporting couples making the transition to parenthood can have broad impact for parents, family relationships, and children's adjustment. Program effects are consistent and benefit all families, with particularly notable effects for families at elevated prenatal risk.

Nearly 13 percent of young adult men report that their biological father has served time in jail or prison; yet surprisingly little research has examined how a father's incarceration is associated with delinquency and arrest in the contemporary United States. Using a national panel of

Genetic studies of delinquent and criminal behavior are rare in spite of the wide recognition that individuals may differ in their propensity for delinquency and criminality. Using 2524 participants in Add Health in the United States, the present study demonstrates a link between the rare 2 repeat of the 30-bp VNTR in the MAOA gene and much higher levels of self-reported serious and violent delinquency. The evidence is based on a statistical association analysis and a functional analysis of MAOA promoter activity using two human brain-derived cell lines: neuroblastoma SH-SY5Y and human glioblastoma 1242-MG. The association analysis shows that men with a 2R report a level of serious delinquency and violent delinquency in adolescence and young adulthood that were about twice (CI: (0.21, 3.24), P ¼ 0.025; and CI: (0.37, 2.5), P ¼ 0.008 for serious and violent delinquency, respectively) as high as those for participants with the other variants. The results for women are similar, but weaker. In the functional analysis, the 2 repeat exhibits much lower levels of promoter activity than the 3 or 4 repeat.