The concept of personality disorders is based on deviant personality t
raits in both the DSM-III-R and ICD-10 classifications. A diagnosis of
personality disorder can be made reliably with structured interviews.
Many individuals are diagnosed with more than one personality disorde
r, and other mental disorders are often found at the same time. Among
the 11 personality disorders in DSM-III-R, only the schizotypal, borde
rline, and antisocial have been examined to any considerable extent fo
r gene effects. The problems of studying heredity are here demonstrate
d for borderline and antisocial personality disorders. Recommendations
are given as to strategies for further study of heredity in personali
ty disorders.