Sammendrag
Background and aims: Substantial correlations between normal and abnormal personality traits have been found, but there is still little knowledge regarding the extent to which the underlying genetic and environmental influences are shared.
Methods: 2,282 Norwegian twins were assessed for DSM-IV criteria for personality disorders using structured interviews. Ten years later years the twins were re-interviewed, and normal personality was assessed using the Big Five Inventory. Multivariate twin models were fitted to the five domains of normal personality and dimensional measures of each of the personality disorders individually.
Results: While the heritability of the number endorsed criteria for the personality disorders ranged from 0.2 to 0.41, the proportion of genetic variance that was unique to each PD ranged from 19% for Avoidant to 79% for Schizotypal, with a median of 58% across all PDs. Conversely, the proportion of environmental variance unique to the personality disorder criteria ranged from 79% to 99%, with median of 97%.
Conclusion: Our results suggest that a considerable proportion of the genetic variance and virtually all environmental variance is unique to the personality disorders, and not shared with the five broad domains of normal personality.
Vis fullstendig beskrivelse