Objective: To calculate heritabilities of personality disorders (PDs) in twin population.
Methods: Based on informed consent, we used Personality Diagnostic Questionnaire (fourth-version) as our screening tool to study the adult twins (aged 20 - 70 years) in Qingdao city. There were 324 twin pairs whose zygosity had been determined. Structural equation modeling was used to estimate the heritabilities by 242 same-sex twin pairs.
Results: The best-fitting models yielded a heritability of 68.26% (60.26 - 74.78) of overall PDs, 59.00% (49.22 - 67.17) of cluster A, 64.99% (56.24 - 72.16) of cluster B, and 63.66% (54.72 - 71.02) of cluster C. There were significant genetic effects for schizotypal, narcissistic and dependent, explaining 49.96% (37.94 - 60.14), 52.89% (41.85 - 62.24) and 68.87% (60.80 - 75.40) of the variance respectively. No genetic effects were found on Histrionic, but common environmental effect accounted for 54.08% (44.50 - 62.43) of the total variances.
Conclusion: PD was mainly determined by genetic factor. These findings may provide evidence for future research on PD.