An inherent challenge in developmental research is to separate the inherently intertwined influences of nature and nurture. We use a host of study designs to tease apart genetic from environmental influences and inform our understanding of development.
A key principle of individual differences research is that biological and environmental factors jointly influence personality and psychopathology. Genes and environments interact to influence the emergence and stability of both normal and abnormal behavior (i.e., genetic predisposition, X, is exacerbated or buffered under environmental conditions, Y, or vice versa), including by shaping the neural circuits underpinning behavior. The interplay of genes and environments is also reflected in various ways in which they are correlated (i.e., rGE). That is, the same genetic factors that give rise to personality or psychopathology also shape that person's environment. In a recent review, we outlined passive, evocative, and active rGE processes and review the findings of studies that have addressed rGE in relation to understanding individual differences in personality and psychopathology across development. Throughout, we evaluated the question of whether it is possible, not only to differentiate the person from their problems, but also to differentiate the person from their problems and their environment. We provided recommendations for future research to model rGE and better inform our ability to study personality and psychopathology, while separating the influence of the environment.