Thanks so much, everyone, for your replies! I now feel quite a bit more secure in my understanding, which is not to say that I completely understand..
I must admit that I'm still a little confused, but I think I'll blame my confusion on not being raised in a Jewish family. It is becoming clear to me that "What is Jewish?" is a religious question with religious answers. It is not a scientific question, so the answers should not be expected to fit into a scientific, "rational" framework. Is that fair to say? Maybe this is why Christain and Jewish people tend to answer the question differently. And neither answer makes complete sense to me, because I am not Christian or Jewish.
It seems to me the truest thing I can say about my heritage is what Spaypets suggests:
>>your ancestors were Jewish (and to be more accurate you might want to clarify by saying "Russian Jews" or "German Jews").
As far as I know, my ancestors were Ukrainian/Polish Jews on my father's side and Scottish/English Presbyterians on my mother's side. And there were probably some atheists and agnostics in there, too. Whew. Glad I got that sorted out! ;-)
Seriously, after all my years in closed adoption, having NO CLUE who my ancestors were, it's truly fantastic to know these tidbits and to be able to claim something of my heritage. (By the way, I also think my heritage includes the wonderful and some not so wonderful experiences I've had in my adoptive family.)
LC
PS: Here's an interesting article that backs up what Elizabeth is saying about biological/cultural race.
http://highered.mcgraw-hill.com/site...ter5/faqs.html