I don't know much about the subject to have an honest opinion of it. I know it is controversial and the researchers didn't reach a conclusion about it yet. I didn't know it was about what causes it. Anyway, I don't really have an opinion.
It is controversial for other reasons too. A lot of psychiatrists don't believe it exists at all. They would aver that it is a type of borderline personality disorder and the actual personality split has not happened and the individual is knowingly playing a role.