The spread of substance use and delinquency between adolescent twins
The spread of twin substance use and delinquency
Article [Accepted Manuscript]
Is part ofDevelopmental Psychology ; vol. 53, no 2, p.329-339
Publisher(s)American Psychological Association
This investigation examines the spread of problem behaviors (substance use and delinquency) between twin siblings. A sample of 628 twins (151 male twin pairs and 163 female twin pairs) drawn from the Quebec Newborn Twin Study completed inventories describing delinquency and substance use at ages 13, 14, and 15. A three-wave longitudinal Actor-Partner Interdependence Model (APIM) identified avenues whereby problem behaviors spread from one twin to another. Problems did not spread directly between twins across domains. Instead, two indirect pathways were identified: (1) Problems first spread inter-individually (between twins) within a behavioral domain, then spread intra-individually (within twins) across behavioral domains (e.g., Twin A delinquency Twin B delinquency Twin B substance use); and (2) problems first spread intra-individually (within twins) across behavioral domains, then spread inter-individually (between twins) within a behavioral domain (e.g., Twin A delinquency Twin A substance use Twin B substance use). Controls for genetic effects, gene-environment correlations, friend substance use and delinquency, and parenting behaviors increase confidence in the conclusion that twin siblings uniquely contribute to the spread of problem behaviors during adolescence. Twin sibling influence is a risk factor for illicit substance use, both because substance use by one twin predicts substance use by the other twin, but also because delinquency in one twin predicts delinquency in the other twin, which then gives rise to greater substance use.