The role of deviant siblings in delinquency: A meta-analysis of longitudinal studies

Abstract

Deviant siblings have been considered as role models for future delinquent behavior; however, previous studies have led to inconsistent results in this regard. The goal of the current meta-analysis was to analyze the effect of deviant non-twin siblings on future delinquency. The potential moderation effects of birth order, sex dyad, age of siblings, publication year, study length, and sample size were analyzed. Six databases were searched for studies: PsycInfo, MEDLINE, Criminal Justice Abstracts, Web of Science, SCOPUS, and Google Scholar. To analyze the prospective interdependence of delinquent siblings, only longitudinal studies were considered for inclusion in the meta-analysis. Two authors independently went through all the retrieved studies and coded those eligible for inclusion, with good interrater agreement. A total of 18 studies were included, which provided 24 independent effect sizes. The meta-analysis showed a significant prospective association between deviant siblings and delinquency. A moderate effect size was found from older sibling to younger sibling and vice versa, as well as between siblings when birth order was not specified. Likewise, significant associations were found in brother pairs, sister pairs, and mixed-sex sibling pairs. No moderation effects were found for age of siblings, publication year, study length, or sample size. The results highlight the role of siblings as a risk factor for future delinquency. • Deviant siblings are prospectively associated with future delinquency. • The effect of siblings is irrespective of birth order, age, and gender dyad. • Publication year, study length, and sample size are not significant moderators.