Development and Psychopathology 27 (2015), 725–746 # Cambridge University Press 2014 doi:10.1017/S0954579414000844 Differential susceptibility to effects of maternal sensitivity? A study of candidate plasticity genes JAY BELSKY, a DANIEL A. NEWMAN, b KEITH F. WIDAMAN, a PHIL RODKIN, b MICHAEL PLUESS, c R. CHRIS FRALEY, b DANIEL BERRY, b JONATHAN L. HELM, a AND GLENN I. ROISMAN d a University of California, Davis; b University of Illinois at Urbana–Champaign; c Kings College London; and d University of Minnesota Abstract Here we tested whether there was genetic moderation of effects of early maternal sensitivity on social–emotional and cognitive–linguistic development from early childhood onward and whether any detected Gene Environment interaction effects proved consistent with differential-susceptibility or diathesis–stress models of PersonEnvironment interaction (N ¼ 695). Two new approaches for evaluating models were employed with 12 candidate genes. Whereas maternal sensitivity proved to be a consistent predictor of child functioning across the primary-school years, candidate genes did not show many main effects, nor did they tend to interact with maternal sensitivity/insensitivity. These findings suggest that the developmental benefits of early sensitive mothering and the costs of insensitive mothering look more similar than different across genetically different children in the current sample. Although acknowledgement of this result is important, it is equally important that the generally null GeneEnvironment results reported here not be overgeneralized to other samples, other predictors, other outcomes, and other candidate genes. The differential-susceptibility hypothesis, which stipulates that some individuals are more susceptible than others to both positive and negative environmental effects, perhaps most especially parenting, has received substantial attention and empirical support in recent years (Belsky, Bakermans- Kranenburg, & van IJzendoorn, 2007; Belsky & Pluess, 2013; Ellis, Boyce, Belsky, Bakermans-Kranenburg, & van IJzendoorn, 2011; Pluess & Belsky, 2009, 2010), including in research on Gene Environment (G E) interaction (Ba- kermans-Kranenburg & van IJzendoorn, 2011; Belsky et al., 2009; Belsky & Pluess, 2009; Berry, Deater-Deckard, McCartney, Wang, & Petrill, 2013). Here we test the specific proposition that a set of 12 candidate “plasticity genes,” se- lected principally on the basis of prior reviews of relevant research (Belsky et al., 2009; Belsky & Pluess, 2009), will moderate the effects of maternal sensitivity on children’s social–emotional and cognitive–linguistic development in a manner consistent with the differential-susceptibility hypothe- sis. Toward this end, we employ two new statistical methods, applying them to longitudinal data collected from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development (NICHD SECCYD; NICHD Early Child Care Research Network [ECCRN], 2005), in response to questions raised about the adequacy and appro- priateness of existing statistical criteria for evaluating differen- tial susceptibility (Belsky, Pluess, & Widaman, 2013; Roisman et al., 2012; Widaman et al., 2012). The application of appro- priate analytic criteria for differential susceptibility is necessary to minimize Type 1 errors and failures to replicate that have fru- strated previous work on candidate genes and broad phenotypes of human cognition, personality, and social behavior (Charney & English, 2012; Deary, 2012; Wacker, Mueller, Hennig, & Stemmler, 2012). Theories of Socialization and Maternal Sensitivity Extraction and genotyping for the NICHD SECCYD was performed at the Genome Core Facility in the Huck Institutes for Life Sciences at Penn State University under the direction of Deborah S. Grove, Director for Genetic Analysis. Genotyping was principally supported by a Research Board grant from the University of Illinois at Urbana–Champaign (to P.R. and G.I.R.). This work was also supported by NSF Grant BCS-0720538 (to G.I.R. and R.C.F.) and by NICHD Grant R01 HD064687 to Rand Conger, which are gratefully acknowledged. Finally, we dedicate this work to the memory of our friend and coauthor Phil Rodkin. In addition to his major contributions to this manuscript, Phil fully embodied the collaborative and collegial spirit that ultimately birthed this contribution to the literature. Address correspondence and reprint requests to: Jay Belsky, Department of Human Ecology, University of California, Davis, 1331 Hart Hall, One Shields Avenue, Davis, CA 95616; E-mail: jbelsky@ucdavis.edu. A central assumption of many developmental perspectives on socialization, whether based, for example, on theories of at- tachment (Ainsworth, 1973; Sroufe, 2000), social learning (Patterson, 1986), or evolution (Belsky, Steinberg, & Draper, 1991), is that parenting matters when it comes to how children develop. Although a myriad of parenting constructs are mea- sured in socialization research, including, for example, author- itative parenting (Baumrind, 1967, 1991), coercive parenting (Patterson, 1986), and mutually responsive relationships (Ko- chanska, 2002), the focus in the present report is on sensitive parenting, a construct emphasized in attachment theory. Ac-