The lack of identified measured environments or genes that are influential for personality development may be potentially related. If gene-environment interplay explains the developmental trajectory of the differential stability of personality, then it is unlikely that specific candidate genes or candidate environments would be directly linked to phenotypic variation. Again, the failures to pin down environmental effects and the problem of missing heritability seem to imply that dynamic processes undergird personality development rather than direct genetic or environmental influences. We have highlighted some of the promising new research in this area, but there remain many unknowns with regard to what environments are influential, when, and for whom. It seems that it will be important to investigate chosen environments (e.g., niche building), dyadic relationships (e.g., peer and parent relationships), and discrete experiences (e.g., stressful life events). Similarly, it will be important to identify when in development and in what environments genetic influences on personality are activated and expressed. Early childhood and adolescence appears to be a time of relative genetic instability with genetic effects decaying in magnitude. Do direct, social pushes
