Growth curve analyses indicated that African-American children’s genotype on the oxytocin receptor gene SNP rs2268493 significantly moderated the intervention format effect on teacher-rated externalizing problems. This finding is particularly important because differential effects of group versus individual delivery were previously found to be evident in teacher reports of children’s behavior at school, but not parent reports of children’s behavior at home (Lochman et al., 2015). For carriers of the G allele, intervention format significantly influenced responsiveness to the intervention. In the group format, children carrying the G allele were less responsive to the intervention, as indicated by teacher ratings of problem behavior one year later, than children in the individual format. In contrast, children with the A/A genotype showed reductions in externalizing behavior regardless of intervention format. The interaction between genotype and intervention condition was not observed for parent-reported externalizing problems.
