The causes of personality disorders are not clear. It seems that several factors interact to form these disorders. However, the main causes of personality disorders seem to be environmental. Most people who are diagnosed with these disorders tend to have experienced trauma at some point in their life.
The causes of trauma include childhood neglect, difficulties growing up, or physical, sexual, and emotional abuse. Children who experience abuse or neglect when growing up do not learn some of the coping mechanisms people use to develop healthy relationships with others. Not all children who experience trauma develop personality disorders, but trauma is a major predictor of personality disorders.