Being an Eastern-European mish-mash Jew, I think it'd be hard to find out "exactly" what I am. I know for a fact that I've got German, Russian, Czech/Yugoslav, and Polish in me, plus a quarter South African (white via Britian, duh). Go back to Great Great Great Grandparents and I'm sure things just get more and more complex.
I find the vagueries annoying....let's keep it simple and say I'm a White American Jew with half South African ancestry. My kids can just be White American Jews. Perhaps all my progeny and their progeny will stay put so we can cut the complications and be White American Jews forever....at least, until Canada conquers us.
You follow the geneology path long enough and we're all hunter/gatherers living on what those people just called "The Land" in whatever language they spoke.
I wonder how many generations Oprah is removed from being Zulu? Her parents couldn't have been slaves, so were both of them of Zulu ancestry? The way she says it, it's as if she's nothing but pure Zulu.