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, but observer-report was only .55. Unfortunately, Saudino (2012) is the only study of early childhood included in the meta-analysis that used both parent- and observer-report. Importantly, there are multiple sources of accurate personality-relevant information (Funder, 1999). These sources of information are differently available to the self (e.g., internal thoughts and feelings), close relatives (e.g., observation of a wide range of behavior from birth), peers (e.g., observation of behavior in an important social context), and trained observers (e.g., observation of a narrow range of behaviors in a controlled environment). Using multiple assessment strategies provides a more complete picture of personality, but there are obvious limitations. Self-report measures are not possible to collect in infants and very young children, and even in middle childhood and early adolescence, the psychometric properties (e.g., reliability, acquiescence, factor coherence, and factor differentiation) and validity of self-report data are less established and at times questionable (Soto, John, Gosling, & Potter, 2008; Tackett et al., 2012). Bridging research
