I also find this discussion very interesting. And I also want to extend the question to those of you who say unconditional love is something you can only feel for your children, or:
I love my daughters. I ask nothing of them and they ask nothing of me, really. (I'm trying to think of anything at all- and can't.) We give to each other, but I don't really think we expect or demand anything of each other. We disappoint each other at times, maybe even get angry at each other occassionally, but none of that erases the love. I've never felt that the love was at risk with either of them. Same with my parents.
So... what if your child was the alcoholic in your life?