I used to believe this. I don't anymore. It's not a completely different personality but taht at least for myself it's all just behaviorally related. In different environments I may act one way vs another and in some ways to an outsider, it may be that it "looks" like multiple personality types but the truth is, it's all me. I am the same person, but one that tends to mold to situations more than other people do. This is not even a bad thing for me, anymore, because I've learned that what it is for me, if I embrace it, is flexibility in being able to be what I need to be for different situations. I'm not sure that it's necessarily a weakness as much as it is a trait of how I am. Basically as I believe very strongly about this, every trait of a personality whether tagged as a "disorder trait" or just simply personality -- has it's positive and negative sides. You can see yourself as lacking identity and now knowing "which" personality you are or you can accept that you are all of them, and each part is just that a portion of teh whole you. Just because they drastically contrast each other does not mean they are an entirely different personality.