Heritability of MMPI personality indicators of psychopathology in twins reared apart

This report presents Minnesota Multiphasic Personality Inventory (MMPI) findings from the Minnesota Study of Twins Reared Apart. Data from 65 unique pairs of monozygotic twins reared apart (MZA) and 54 unique pairs of dizygotic twins reared apart (DZA) were analyzed. As in other results from this sample, MZA twins evidenced substantial similarity, highlighting the influence of shared genes. Biometric modeling yielded estimates of heritability for the MMPI's standard validity and clinical scales and for the Wiggins content scales ranging from .26 to .62 (M = .44), echoing previous findings from the twin and adoption literature on personality. The pattern of MZA and DZA correlations suggested nonadditive genetic effects for 3 MMPI scales. Multivariate profile analyses also suggested genetic influence on both profile elevation and shape.