Understanding Family Process and Child Adjustment Through Behavioral Genetic Research: A Reply

The contribution of both genes and environments on family relationships is reviewed in Horwitz and Neiderhiser (2011). This recognition is due to two simultaneous movements in the fields of both family process and behavioral genetics. Specifically, family researchers have been incorporating strategies that allow for the estimation of genetic effects in their studies and genetic researchers have been directly measuring family processes. The commentaries by Calkins (2011) and Deater-Deckard (2011) help to highlight the promise and limitations of this work to date and, together with our article, provide guidance for where this work can and should go in the future. In all three papers the focus is clearly on moving beyond simply examining genes and environments as independent factors. Instead, there is both a need and an emphasis on how genes and environments work together. We welcome the opportunity to both expand on the article and to use the suggestions made in the commentaries to discuss current and future directions of research on gene - environment interplay. Three points will be made in this response. First, in conjunction with the comments made by Deater-Deckard, we discuss how work in gene - environment interplay may be expanded to clarify different processes in different dyads within the family system. Second, we use emerging work in gene - environment interplay to elaborate on mechanisms. Specifically, in response to the comments made by Calkins, we describe work that is engaged in disentangling genes, environments, and potential underlying biological processes. Third, we discuss improvements that must be made in both family research and genetic research in order to advance our understanding of gene - environment interplay within the family. Throughout each of these sections we integrate the suggestions and comments of both Calkins and Deater-Deckard with our article to present a unified set of recommendations for the fields. GENE -ENVIRONMENT INTERPLAY AS A STRATEGY FOR UNDERSTANDING FAMILY PROCESS Deater-Deckard underscored the importance of behavioral genetic work for delineating sources of within-family variation in qualities of each family relationship and each child's outcome. Indeed, by demonstrating when genetic or environmental influences, or both, contribute to these associations we have discovered that different dyads within the family influence family relationships and child functioning for different reasons (e.g., Reiss, 2010). For example, genetic influences have been found to account for a sizable portion of the association between hostile and critical parent -adolescent interactions and adolescent antisocial behavior. This suggests that children's heritable characteristics evoked interactions with parents that in turn contributed to their maladjustment (e.g., Reiss, 2010). Additional work has demonstrated that shared environmental influences accounted for the majority of the covariation between mother -child and sibling relationships, indicating that siblings model their relationships with their mother when siblings interact with one another (Bussell et al., 1999). Sibling relationships were also linked to a broad range of adolescent adjustment measures, and shared environmental influences contributed to these linkages (Reiss, Neiderhiser, Hetherington, & Plomin, 2000). Together, this set of findings indicates that children's genotypes are important for understanding their relationships with their mothers, whereas siblings are important for shaping each others' adjustment. Hence, this work illustrates the utility of behavioral genetic research for delineating sources of within- family variation in qualities of each family relationship and each child's outcome. Deater-Deckard further raised the need for more research focused on differentiating individual-level processes (i.e., actor and partner effects) from dyadic level processes using the behavioral genetic extension of the social relations model. …