Evidence for a gene–gene interaction in predicting children's behavior problems: Association of serotonin transporter short and dopamine receptor D4 long genotypes with internalizing and externalizing behaviors in typically developing 7-year-olds

Recent work on the molecular genetics of complex traits in typical and atypical human development has focused primarily on associations of single genes with behavior. Disparate literature suggests that the presence of one or two copies of the short allele of the serotonin transporter (5-HTT) gene and the long allele (7-repeat allele) version of the dopamine receptor D4 (DRD4) gene predicts internalizing- and externalizing-related behaviors, …