Substance use and substance use disorders run in families. While it has long been recognized that the etiology of substance use behaviors and disorders involves a combination of genetic and environmental factors, two key questions remain largely unanswered: i) the intergenerational transmission through which these genetic predispositions are passed from parents to children, ii) the molecular mechanisms linking genetic variants to substance use behaviors and disorders. This article provides an overview of innovative approaches leveraging family- and genomic-based analyses to reveal how family environments and genetic risks, including variation in gene expression, jointly contribute risks of substance use behaviors and disorders. We also describe two longitudinal cohorts - the Brisbane Longitudinal Twin Study in Australia and the Lifelines Cohort Study in the Netherlands - that will be used to apply these methods.
Keywords: Substance use, substance use disorders, genetic nurture, non-transmitted alleles, gene co-expression network