I would say that personas are what we choose; you have your teacher self, your home self, your public self.... maybe your PC self..... I used to have my home self, school self. church self.... but they were the "different hats" i would wear depending on where I was.
That said, when i switch into a different alter, 8 is 8. there is no me who is 32, there is no adult self present. or when 10 comes in and wants to destroy everything within range or acts on the self, or when 22 comes in and starts drinking because she's an alcoholic.... make any sense?
kiya