A longitudinal family study of personality change and stability.

The 19-year stability of personality from late adolescence to early adulthood was examined in a sample of 121 men and women who had participated in an earlier study of articulation and language development (Templin, 1966; Templin & Glaman, 1976). Personality was assessed using the Eysenck Personality Inventory (EPI). At the time of retest, personality data were also collected from the participants' mothers. Modest stability of individual differences in personality was observed, consistent with the literature on longitudinal studies of personality during late adolescence and early adulthood. For the Extraversion and Neuroticism scales, offspring means decreased significantly over the 19-year period such that the offspring means were closer to the mean scores of their mothers when they were followed up in adulthood as compared to their first testing in adolescence. There was, however, no change in mother-offspring resemblance from the initial test to retest. Mother-offspring resemblance appears to be due largely to aspects of personality that were stable from adolescence to early adulthood. Implications of these results are discussed in relation to the findings of previous longitudinal studies of adult personality and recent behavioral genetic evidence regarding personality change and stability.