One of the things that will never get explained in the films is how Ben was able to retain his identity, because it happened somewhere between the third and fourth movies. I set up that this is a discipline that he learned from Yoda; Yoda told him how to do that.
Sorry. i just can't seem to help myself. My brain is freaking out. Two predawn mornings in a row. It doesn't know what to think, how to act. I'll have a talk with it later. Perhaps get it some counseling.