Grant: Project Grant

Externalizing behaviours (EXT) refer to aggressive, hyperactive/impulsive, and oppositional behaviours that disrupt the social environment, and lead to difficulties such as academic underachievement, substance misuse, and health problems. EXT emerge from an array of genetic and environmental factors interacting over time and across generations. Understanding EXT thus requires a longitudinal approach that starts early in life, runs across generations, and accounts for the role of genes and the environment in the transmission process. The goal of this research is to characterize the role of the family in the intergenerational transmission of EXT. We will assess parents' and child's genetic propensity toward EXT, and consider key family environments as possible mediators of genetic and environmental transmission pathways from parent to child. We will use multiple measures of EXT in three birth/pregnancy cohorts from early childhood to adolescence: the Quebec Newborn Twin Study, the Quebec Longitudinal Study of Child Development, and the 3D Cohort Study. We will measure four polygenic propensity scores associated with EXT in both parents and children to disentangle direct and indirect intergenerational transmission pathways using sex/gender-informed approaches. We will test if family environments, such as unhealthy prenatal environment, quality of parental care and supervision, and family SES partly explain parent-to-offspring similarity in EXT via indirect genetic transmission or environmentally-mediated pathways. Our team consists of emerging, mid-career, and established researchers, with a strong track record of successful collaborations. The unique longitudinal examination of intergenerational transmission of EXT will inform preventive intervention efforts. This will create Canada's first developmentally, genetically, and environmentally informed platform to better understand the intergenerational continuity of traits and behaviours, extending beyond EXT.