This study investigated whether children scoring higher on a polygenic plasticity index based on five dopaminergic genes (DRD4, DRD2, DAT1, MAOA, and COMT) benefited the most from the Incredible Years (IY) parent program. Data were used from a randomized controlled trial including 341 Dutch families with 4- to 8-year-old children (55.7% boys) showing moderate to high levels of problem behavior. IY proved to be most effective in decreasing parent-reported (but not observed) externalizing behavior in boys (but not girls) carrying more rather than fewer dopaminergic plasticity alleles; this Gene 9 Intervention effect was most pronounced in the case of boys whose parents’ manifested the most positive change in parenting in response to the intervention. These results proved robust across a variety of sampling specifications (e.g., intention to treat, ethnicity),
Child Development

Chhangur, R., Weeland, J., Overbeek, G., Matthys, W., Orobio de Castro, B., Van der Giessen, D., & Belsky, J. (2016). Genetic moderation of intervention efficacy: dopaminergic genes, the Incredible Years, and externalizing behavior in children. Child Development. doi:10.1111/cdev.12612