Allergies are biological, not phsychological. The only thing simmilar would be a phobia that one personality does not have. This report I did wuickly on multiple personality disorder should explain it to you a bit. It was just a quick thingy following some guidlines.
Multiple Personality Disorder
(Dissociative identity disorder)
Multiple Personality Disorder (otherwise known as Dissociative Identity Disorder) is when one individual has 2 or more conscious personalities inside of one mind. These conscious(s) must both take control over the person for an amount of time, with the associated memory loss from that period of time.
Multiple personality disorder can be caused by many things. Physical and sexual trauma are some of the leading causes, possible because the subjects mind was desperate to escape the situation, badly enough to have to make another personality. Brain scans of people with multiple personality disorder show changes on blood flow in areas of the brain such as the cerebral cortex.
People of all ages are susceptible to multiple personality disorder. It does not matter how old you are, but the right physical conditions and possibly the experiences that the individual has gone through. People who have experienced trauma are much more likely to develop multiple personality disorder.
Multiple personality disorder can affect people lives in many devastating ways. The switching of personality leaves the other personality with a gap in it’s memory. This could lead to the other personality ending up in a situation that the other personality got into, possibly a job or a troublesome situation. The person could have committed a crime, and ended up in jail, but then the other personality would emerge, and the person would have no idea what is happening.
Multiple Personality Disorder has no cure. Because the disorder changes, it is unique to each and every patient. It has no strict guideline of causes because it can be caused from many things, from trauma to brain defects. This makes getting to the root of Multiple Personality Disorder very difficult, and finding a cure near impossible. There has been research into therapy, with just the one person, or in a group. Both cases have proved mostly ineffective, and difficult. Also, a moral question comes to mind. If you could remove a personality from the subject, which one would it be? Sometimes you might not be able to tell which one is the original. What if the second personality has important regressed memories from the other personality. What effects would take place from having one personality eradicated? The effects cannot possibly be known, the only way to find out would be to remove one personality from someone, with possibly lethal results. Perhaps advances in psychology and technology will find a way to remove one personality, or merge the two together.