heritability and environmentality of traits at one point in time; (2) the test-retest stability of phenotypic traits and of genetic and environmental effects; and (3) the contribution of genetic and environmental effects to test-retest stability. Based on our review above, the FFT would predict that genetic effects are large (i.e., high heritability), stable (i.e., high rA), and explain increases in phenotypic stability (i.e., age-trends in genetic contribution parallel to age-trends in phenotypic stability). According to this perspective, environmental effects are likely measurement error (i.e., substantial environmentality, but very low corrected environmentality), time point-specific (i.e., low rE), and unstructured in terms of the life course (i.e., minimal environmental contribution to age-trends in phenotypic stability). SPMs, on the other hand, would predict that genetic influences on personality and increases in stability exist (i.e., non-trivial estimates of heritability, rA, and genetic contribution), but increases in phenotypic stability would be primarily mediated by increasingly stable environmental factors (i.e., increasing environmentality and rE with age).
