Our results are also congruent with our previous analysis in this sample of the structure of genetic risk factors for personality disorders (27). That study, which examined only the 10 personality disorders, identified three genetic factors, the first of which loaded most heavily on histrionic, narcissistic, and borderline personality disorders—clearly reflecting our axis II externalizing factor. The second factor loaded more specifically on antisocial and borderline personality disorders—approximating our broader axis I externalizing genetic factor. The third genetic factor loaded most heavily on avoidant and schizoid personality disorders, with weaker loadings on dependent and schizotypal personality disorders—reflecting our axis II internalizing genetic factor.
