Twin relationships: A comparison across monozygotic twins, dizygotic twins, and nontwin siblings in early childhood

Abstract

Abstract Twin relationships remain understudied despite the increasing prevalence of twinning and the unique influence it entails for individual development and family functioning. The current study assessed closeness, conflict, dependence, and rivalry within 1281 pairs of 3-year-old twins via maternal reports. Relationship quality was compared based on the twins' zygosity and dyadic sex-composition. As expected, monozygotic (genetically identical) twins were perceived as closer and more co-twin dependent relative to dizygotic (fraternal) twins. Same-sex twins were reported to have lower dependence and higher levels of conflict and rivalry than opposite-sex dyads. As compared with a matched sample of 84 nontwin siblings, dizygotic twins were described as closer and more co-dependent. Findings emphasize the need to consider the special nature of the twin relationship and lend support for theories regarding the effects of genetic similarity and gender in shaping interpersonal relationships. Keywords: twinstwin relationshipssibling relationshipsLIST