2023

Bullying research has shown repeatedly 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 maladjustment. However, genetic vulnerability may confound the reported associations. This study examined to what extent genetic vulnerability can account for the reported associations between bullying involvement (age 11-14) and later internalizing and externalizing problems (age 16), using data from the TRacking Adolescents' Individual Lives Survey (n = 1604). Because polygenic scores capture only a fraction of the total genetic effect, they were extrapolated to the size of single-nucleotide polymorphism and twin heritability estimates to examine genetic confounding while controlling for (hypothetical) polygenic scores that fully capture the genetic effect. Genetic vulnerability for internalizing and externalizing problems confounded, respectively, the association between bullying victimization and later internalizing problems, and the association between bullying perpetration and later externalizing problems. As such, this study showcases a method that can be broadly used to assess the magnitude of genetic confounding. Caution is, however, warranted in interpreting particularly the less straightforward extrapolations of polygenic scores to the size of twin heritability estimates.

We applied network analysis combined with community detection algorithms to examine how adverse experiences (AEs) (e.g., abuse, bullying victimization, financial difficulties) are, individually and conjunctively, associated with emotional and behavioral problems at age fourteen in the Dutch TRacking Adolescents' Individual Lives Survey (TRAILS, N = 1880, 52.2% female). We found that bullying victimization, peer rejection, parental mental health problems, emotional abuse, and sexual abuse were the only AEs directly contributing to risk of emotional problems. Parental divorce and emotional abuse were the only AEs directly contributing to risk of behavioral problems. Most AEs (e.g., parental employment, parental physical illness) were not conditionally associated with emotional and behavioral problems but may nevertheless contribute to emotional and behavioral problems via associations with other AEs (e.g., parental unemployment and emotional abuse). Community detection algorithms suggested that many of the AEs cluster together (e.g., physical abuse, emotional abuse, and sexual abuse; financial difficulties and parental unemployment), sometimes with emotional and behavioral problems (e.g., bullying victimization, peer rejection and emotional problems). Our findings shed light on how individual AEs contribute to risks of emotional and behavioral problems directly, and indirectly through associations with other AEs.