What causes a personality disorder?

Research about personality disorders suggests that a combination of factors is involved.

Family circumstances

There is some evidence to suggest that family circumstances can make you vulnerable to a personality disorder. This might be because you had a difficult childhood. You may have had changes in your family that meant you had several different parent figures, with different demands and expectations, or you may have spent time in foster care. If you experienced physical, sexual or emotional neglect or abuse (many people with borderline personality disorder [BPD] report that this is the case), this may make you more vulnerable.

It is difficult to learn how to have normal trusting relationships if the people you are dependent on do not provide security, or it comes with abuse. This may make you feel that you are worthless, make you prone to anger, and you may find it difficult to express your emotions safely. If you have had to adapt to different parental figures, you may never have learned to trust others, or to understand other people’s feelings or body language, and may be suspicious of their intentions towards you. In turn, if you seem aggressive and hostile, others will be suspicious of you and avoid you, and this will make the problems worse.

Antisocial personality disorder (ASPD) has been linked to antisocial behaviour in childhood, which could be the result of high levels of stress and family problems. These might include your parents not giving you enough warmth, intimacy, consistency or appropriate discipline and supervision. Your parents having ASPD or abusing drugs or alcohol may also be factors.


Repeated childhood traumas (unrelated to abuse), such as being involved in major incidents or accidents, or sudden bereavement, may lead to personality disorder. It has been suggested that early and severe trauma, in particular, can cause personality difficulties.

This is not to say that everyone who experiences a traumatic situation will develop these problems, just that it might leave someone more vulnerable. However, the way you and others around you reacted and dealt with it, and the support and care you received to help you cope, will have made a lot of difference.

“I have narcissistic borderline personality disorder. At first it was difficult to accept that the problem was essentially ME… my personality… But then… being able to put it into perspective as a developmental flaw was much easier to accept – that it was simply the way I’d developed in response to my environment and situations I’d experienced.”

Genetics and inheritance

Some elements of our personality are inherited. People are born with different temperaments; for example, babies vary in how sociable they are, in the intensity of their reactions, and in the length of their attention span. Some experts believe that inheritance may play a relatively big part in the development of OCPD (obsessive compulsive) and ASPD (antisocial), and that there may also be a genetic link between personality disorders and certain other mental health problems; for example, schizophrenia or bipolar disorder.

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