Childrenʹs reactions to the unfamiliar in middle childhood and adolescence: an observational twin/sibling study

This report presents the results of a twin/sibling observational study of childrenʹs reactions to the unfamiliar. The investigation was designed to examine genetic and environmental contributions to childrenʹs social and exploratory behavior in novel contexts during middle childhood and adolescence. The study included 156 children in 78 same-sex dyads (20 MZ twin pairs, 19 DZ twin pairs, and 39 full sibling pairs) between the ages of eight and 14 years old and their mothers. Each member of the sibling dyad was filmed in three situations (with an unfamiliar adult, alone, and with an unfamiliar peer) in a structured laboratory setting. Mothers’ reports of the childrenʹs extraversion and emotionality were significantly correlated with childrenʹs reactions to the unfamiliar. There were significant genetic and nonshared environmental contributions to childrenʹs behaviors in all three contexts. There were also significant genetic contributions to stability in childrenʹs exploratory behavior from the adult to the peer situation, but not from the alone setting to the adult or to the peer settings. The importance of genetic contributions and context effects for understanding personality differences during middle childhood and adolescence is discussed.