Genetic Confounding in Peer Bullying Research (oral presentation at LHRS)


Bullying research has provided ample evidence that victims of bullying have an increased risk for later internalizing problems and bullies have an increased risk for later externalizing problems. Bullying involvement is often, either explicitly or implicitly, presented as part of a causal mechanism for such maladjustment. Genetic vulnerabilities are usually not taken into account, although these may confound the reported associations. In the present study, we investigated to what extent genes account for the reported associations between bullying involvement and later internalizing and externalizing problems, using data from the longitudinal TRacking Adolescents' Individual Lives Survey (TRAILS; N = 1604). We examined whether polygenic scores of internalizing and externalizing problems confounded associations between self-reported bullying involvement (age 11-14) and later internalizing and externalizing problems (age 16). Because polygenic scores capture only a small part of heritability, we used a recently proposed method (Pingault et al., 2021) that incorporates SNP heritability and twin study-based heritability estimates. Genetic vulnerability for internalizing problems confounded the association between bullying victimization and later internalizing problems. When using polygenic scores, we found very small effects but when incorporating a twin-based heritability estimate, genetic vulnerability almost completely explained the association. Similar results were found for the link between bullying perpetration and later externalizing problems. Our findings suggest that a shared genetic predisposition may link bullying involvement to later internalizing and externalizing problems, rather than causal relations between bullying involvement and internalizing and externalizing problems. This study showcases a method that can be broadly used to assess genetic confounding.

Jul 11, 2022 — Jul 13, 2022