The identified linear and non-linear trends are apparent in Figure 5 with reference to the expected exponential lifespan trend for phenotypic stability plotted in green. In infancy, phenotypic stability equals the genetic contribution to stability, and genetic effects exert an impressive and almost constant influence on stability across the entire lifespan. However, increasing environmental stability, from negligible in childhood to almost equivalent importance in old age, is entirely responsible for increasing phenotypic stability. This trend is consistent with that found in Figures 3 and 4. Genetic influences increase in stability across development, but the total variation in personality associated with genetic differences decreases across the lifespan. This tradeoff results in a nearly constant genetic contribution to phenotypic stability. Both environmentality and environmental stability increase across the lifespan. Thus, the combination of environmental effects persisting to later ages to a greater extent and accounting for personality variance to a greater extent results in an increasing environmental contribution to phenotypic stability across the lifespan.
