We constructed connected-linear and continuous exponential models of: (1) age-trends in the level of heritability, environmentality, and corrected environmentality across the lifespan; (2) age-trends in stability at the phenotypic, genetic, environmental, and corrected environmental level across the lifespan; and (3) age-trends in the contribution of genetic and environmental effects to phenotypic stability across the lifespan. For the first set of analyses (in which the outcomes are specific to individual time points), each outcome was predicted by the associated age. For the second and third sets of analyses (in which the outcomes are derived from longitudinal pairs of time points), the outcome was predicted by age at baseline controlling for time interval between measurements. In all models, we did not adjust the coding of participant age, and therefore, the intercept of the model applies to age 0. As the earliest effect size occurs at age 1, this approach requires a very minor extrapolation. Additionally, we explicitly vary participant age in our interpretation and figures. In all models based on longitudinal data, we control for the linear effect of time lag, which
