Behavioral Disinhibition Model of Addiction: A review and new findings from the Minnesota Twin Family Study

We provide an historical perspective on the development, empirical support, and evolution of the behavioral disinhibition theory of addiction that has been a central aim of the Minnesota Twin Family Study (MTFS). Conceived by David Lykken, the MTFS initiated a 35-year collaboration between Matt McGue and Bill Iacono, who together built the Minnesota Center for Twin and Family Research (MCTFR). The behavioral disinhibition model posited that a heritable psychobiological liability expressed as the failure to conform to normative behavior and deficits in self-regulation underlies the co-occurrence, family transmission, and early onset of substance use problems and externalizing psychopathology. MCTFR longitudinal investigations spanning childhood through adulthood and twin, adoption, family, and genome-wide association studies support the genetic basis of behavioral disinhibition and its associations with numerous impulse control problems. Heritability of externalizing peaks in late adolescence, while there is consistent evidence for shared environmental influences on child antisocial behavior and early adolescent problem behaviors. Environmental adversity amplifies genetic vulnerability, driving an adolescent onset of substance use problems while behavioral disinhibition is key to their persistence. We also present an updated behavioral disinhibition model that spans childhood through young adulthood and report novel cotwin control analyses of 1382 twin pairs finding that heavy substance use has robust casual non-familial effects that contribute to greater antisocial behavior and a more disinhibited personality structure in adulthood. Genetic and shared environmental influences on behavioral disinhibition and the non-familial effects of heavy substance use create a system of person-environment transactions that maintain stable developmental trajectories and changes in adjustment across young adulthood.