Hi b_b, thx for your comments. "I know who I am at hockey, because I put on the number 11 sweater" - great line. First of all, it's absolutely encouraged to answer a question with a question. The practice goes back to the Bible:
God: Cain, where is Able your brother?
Cain: Am I my brother's keeper? Second, it's great that you feel singular and integrated in your me-ness. I feel that way too, and hope I am mostly consistent in my self-presentation (regardless of the particular role).
My question came out of my close observation of another who is struggling with the falling away of one identity (scientist actually), and can't seem to self-define without it. I imagine there are other contributing circumstance. I love the diversity in your life. Those of us who are lucky perhaps move through all these identities in an integrated way. All your identities will make it easier to cope in case one or more of the key ones are threatened. (A huge topic - identity - that I visit lightly from time to time.)
I'm not sure I'd use the parable of Cain and Abel as my model to live by! Thanks for the vote of confidence though :) Any teachers reading this? I think you guys have a life in which multiple versions of yourself might be the most pronounced, given the pressures to set a good example for young people.