77. Deater-Deckard, K., & O'Connor, T.G. (2000). Parent-child mutuality in early childhood: Two behavioral genetic studies. Developmental Psychology, 36, 561-570.

Parent-child mutuality (shared positive affect, responsiveness, and cooperation) is an important component of family socialization process. We extended previous research on mutuality by examining sibling differences and gene-environment processes using a quantitative genetic design applied to observations of mutuality and parents' and observers' rating of family environment and child behavior. The first study included 125 pairs of identical and same-sex fraternal three-year-old twins. Greater mutuality was associated with higher socioeconomic status. Moderate sibling similarity in parent-child mutuality was accounted for by child genetic similarity, suggesting evocative gene-environment correlation and nonshared environmental processes. These findings were replicated in a second study of 102 pairs of adoptive and biological siblings.