Fourth, the moderation analysis may have been underpowered if there was not sufficient data density across levels of the moderator for the entire lifespan. This limitation may be particularly relevant for self- compared to informant-report format as parent-report is primarily used in early childhood and self-report is primarily used in adulthood. Although we found very consistent results with respect to age trends in stabilities and contributions to stability when analyses were restricted to effect sizes from only self-report data, the age trends in heritability and environmentality appeared weaker when only self-report data were used. If the most dramatic changes in heritability and environmentality primarily occur in the first decade of life, then analyses of only self-report data (which do not contain data from infancy and early childhood) may not be well-equipped to detect them. However, it is also possible that parents tend to exaggerate differences between their (non-monozygotic) children which acts to magnify heritability estimates in early childhood (Saudino & Cherny, 2001). For example, Saudino (2012) found that the heritability of activity level at age 2 was .84 for parent-report,
