Biopsychosocial Models and the Study of Family Processes and Child Adjustment

In their review, Horwitz and Neiderhiser (2011) provided a thorough discussion of the most recent behavior genetics research that addresses the issue of whether, and under what conditions, genetic factors and family processes are jointly implicated in child behavioral outcomes. The goal of examining the potential gene–environment interplay (GE) on family relationship factors known to be integral to child adaptive functioning is laudable and timely. As Horwitz and Neiderhiser noted, the “independent” effects of genes and environment have been examined in considerable prior research. In addition, and perhaps more importantly, most recent models of genetic influences on both parenting and child behavioral outcomes have discarded any notion that such influences are ever independent of the environment (Meaney, 2010). Family researchers are also beginning to appreciate the converse: any examination of the family’s influence on child functioning must, of necessity, acknowledge that such effects occur in the context of a host of biological processes, whether measured or not (cf., Booth, McHale, & Lansdale, 2011). Thus, behavior genetics research must be evaluated in a light of a broader biopsychosocial framework that acknowledges the complex feedback processes that occur across development (Michel & Moore, 1995). The work reviewed in the Horwitz and Neiderhiser article, although broad and inclusive, leads to several general conclusions regarding the interplay between genetic factors and family environmental experiences. Genetic factors, operationalized by the authors in terms of “heritable” traits that are observable in either parents or children of varying degrees of biological relatedness, work in concert with parenting behavior to create multiple pathways to child adjustment. Sometimes, these factors are correlated and thus create opportunities for transactional child–environmental influences. Other times, the environment moderates a genetic pathway, again indexed by some trait that is observed in either the parents or the child, to produce different outcomes. And, perhaps most importantly, environmental factors may not be reliably predictive of specific outcomes, as they seem to have differential effects on the behavioral phenotype of a particular inherited trait depending on both the specific dimension of parenting observed and the particular outcomes of interest. Such findings are of use to researchers studying child and family processes for a variety of reasons, some of which the authors of the review articulated. Studies of GE processes illuminate the shortcomings of direct effects models from a scientific perspective and offer guidance as to points of entry for prevention and intervention in children and families at risk for poor outcomes. But, the usual caveats to the conclusions drawn by such a review are in order. First, behavior genetics research may provide inferences about general principles that govern GE interplay, but it is largely silent as to the actual mechanism of transmission. That is, these studies tell us merely that GE processes are at work in some specified developmental pathway, not, contrary to what the authors sometimes implied, how these essentially biological factors actually lead to a specific behavioral outcome such as child adjustment. Second, behavior genetics research focuses on observed traits, and provides no indication of which genes may be involved in producing which behavioral outcomes. So, although behavior genetics studies can point us in the direction of promising moderators and reveal whether and under what conditions a behavioral phenotype might be expressed, they cannot explain the pathway from gene action to outcome. This is a critical omission because, as recent molecular genetics research makes clear, the nature of GE depends in a non-trivial way on a host of intervening processes occurring across multiple biological and behavioral levels of an organism’s functioning across time (Johnston & Edwards, 2002). Finally, behavior genetics research typically focuses on environmental factors that have previously been studied as main effect predictors of outcomes, like parental warmth and control in early childhood. This narrow and somewhat static interpretation of “E” doesn’t itself preclude the possibility that other aspects of the child’s environmental experience are operating on the gene’s action, as they clearly are, but it tends to reduce GE to a single event and it obscures potent biological and behavioral factors that are likely important as well. Indeed, as Shanahan and Hofer (2005) noted, the E in GE might best be conceptualized as “exposure,” a term that highlights the range of processes that may alter the pathway initiated by the gene’s cellular action at biological and behavioral levels across development. Thus, although Horwitz and Neiderhiser provided behavioral scientists with a good first step toward greater understanding of the role of genetics in the complex trajectories that characterize family influences on development, their review also raised a number of issues that are clearly in need of further elaboration. In this commentary, and against the backdrop of a biopsychosocil perspective, I articulate four such issues that are challenging our field, both conceptually and empirically, and that must be confronted in any analysis of GE effects on children’s adjustment. These issues include greater specification at the levels of theory, mechanism, phenotype, and development.