"Under a certain condition in the split personality disorder, a single personality can split into two, and two personalities into four, and so on. As for how many times this can take place, there's no detailed record to-date. The highest known record is twenty-one personalities."
"Can a split personality disorder really become a multiple personality disorder?"
"A split personality develops, simply put, when there is too much pain for a person to bear. Therefore, the mental state gives rise to the development of a second personality out of a self-protection mechanism. Then, when the split personality evolves into multiple personalities, it means that the mental mechanism has already begun to create a personality society. This personality society can be self-created by the patient, or it can be created through manipulation by some external means."
