Beyond Diathesis Stress: Differential Susceptibility to Environmental Influences Jay Belsky and Michael Pluess Birkbeck University of London Evolutionary-biological reasoning suggests that individuals should be differentially susceptible to envi- ronmental influences, with some people being not just more vulnerable than others to the negative effects of adversity, as the prevailing diathesis-stress view of psychopathology (and of many environmental influences) maintains, but also disproportionately susceptible to the beneficial effects of supportive and enriching experiences (or just the absence of adversity). Evidence consistent with the proposition that individuals differ in plasticity is reviewed. The authors document multiple instances in which (a) phenotypic temperamental characteristics, (b) endophenotypic attributes, and (c) specific genes function less like “vulnerability factors” and more like “plasticity factors,” thereby rendering some individuals more malleable or susceptible than others to both negative and positive environmental influences. Discussion focuses upon limits of the evidence, statistical criteria for distinguishing differential suscep- tibility from diathesis stress, potential mechanisms of influence, and unknowns in the differential- susceptibility equation. Keywords: parenting, differential susceptibility, diathesis stress, GXE, psychopathology Students of human development appreciate that individuals vary in whether and/or the degree to which they are affected, over the shorter and longer term, by environmental experiences, including child-rearing ones. Perhaps the most striking evidence that person characteristics condition or moderate environmental effects is to be found in developmental research on Temperament  Parenting interaction (Rothbart & Bates, 2006) and psychiatric research on Gene  Environment interaction (GXE; Burmeister, McInnis, & Zollner, 2008). Work in both these areas of inquiry is guided primarily, even if not exclusively, by what developmentalists regard as the transactional/dual-risk model (Sameroff, 1983) and what psychia- trists and others studying and treating psychopathology regard as the diathesis-stress model (Monroe & Simons, 1991; Zuckerman, 1999). Central to both these frameworks is the view that some individuals, due to a “vulnerability” in their make-up—which may be behavioral/temperamental in character (e.g., difficult tempera- ment), physiological or endophenotypic in nature (e.g., highly physiologically reactive), or genetic in origin (e.g., 5-HTTLPR short alleles)—are disproportionately or even exclusively likely to be affected adversely by an environmental stressor. That stressor may be child maltreatment, insensitive parenting, or negative life events, to name but three that are well studied and figure promi- nently in this paper, which advances an alternative to the diathesis- stress/dual-risk model of environmental influences and human development. According to prevailing views, it is the child with a “difficult” (or negatively emotional) temperament, for example, or individu- als carrying certain “vulnerability genes” or “risk alleles” who are most likely to develop or function poorly, such as by manifesting a psychopathological condition (e.g., depression), when exposed to a stressor of interest. The dual-risk designation derives from the synergistic effect of a risk (or diathesis) inherent in the individual interacting with one operative in the environment. The point of this paper is not so much to challenge the view that diathesis-stress phenomena exist or that processes related to them operate. That seems incontestable. Nor is its intent to suggest that diathesis- stress thinking and research have proven unproductive, either theoretically or empirically. That, too, seems indisputable. Rather, the goal in this effort is to assert—and demonstrate empirically—that in many cases where dual-risk/diathesis-stress processes appear to characterize human functioning and develop- ment, something of equal or perhaps even greater significance is going on. Indeed, it is our contention that this “something else” is often missed as a result of expectations derived from the prevailing conceptual perspective that guides both inquiry and interpretation of findings. In fact, it is a central claim here that the dispropor- tionate attention paid to the negative effects of contextual adver- sity, broadly defined and varied in its operationalization, on prob- lematic functioning and disturbances in development and mental Jay Belsky and Michael Pluess, Institute for the Study of Children, Families and Social Issues, Birkbeck University of London, 7 Bedford Square, London WC1B 3RA, United Kingdom. Preparation of the manuscript was supported by Swiss National Science Foundation Grant PBBS1—120809, a grant for doctoral studies awarded to Michael Pluess. Special appreciation is expressed to Terrie Moffitt for strongly encouraging the preparation of this article, to Bruce Ellis for clarifying our understanding of the biological-sensitivity-to-context thesis, and to Marinus van IJzendoorn and Marian Bakermans-Kranenburg for sharing ideas and stimulating our thinking regarding mechanisms of bio- logical action. Correspondence concerning this article should be directed to Jay Belsky, Institute for the Study of Children, Families and Social Issues, Birkbeck University of London, 7 Bedford Square, London WC1B 3RA, United Kingdom. E-mail: j.belsky@psychology.bbk.ac.uk Psychological Bulletin © 2009 American Psychological Association 2009, Vol. 135, No. 6, 885–908 0033-2909/09/$12.00 DOI: 10.1037/a0017376 885