Classification of Wizarding Genealogy (or, What Makes a Halfblood).

This is coming from me and my bro while we rewatch OotP...

Harry is a Halfblood.
He has 2 wizarding parents, but 2 Muggle grandparents as well as 2 wizarding grandparents.

Voldemort is a Halfblood.
He has a Muggle father and a wizarding mother.
But he has he same grandparentage as Harry.

So, does your wizarding heritage come from your parents or your grandparents?
I thought it was parents, but I could be wrong.
And what would that make Harry/Ginny's kids and Ron/Hermione's kids?

I remember reading someone's explanation of half-blood. They compared it to term as used by the Nazis during the Holocaust when referring to a person's Jewish hertiage. If you were a half-blood, you had at least one Jewist grandparent, if I remember correctly. So Harry and Ginny's children would be half-bloods, in my mind, because their one grandmother (Lily Evans-Potter) was of Muggle blood. Even though Lily is a witch, her value is equal to that of a Muggle in the minds of the Death Eaters. Ron and Hermione's children would also be half-bloods because two of their grandparents (Mrs. and Mr. Granger) were of Muggle blood.

Hope that makes some sort of sense.

I get the feeling any nonmagical blood in your lineage discounts you from being a Pureblood. Or at least by elitest standards. I think if you have two wizard parents, you are considered some kind of normal, maybe without a name attached. And I always just figured Halfblood meant one of your parents was a muggle and the other magical. -shrug- I guess it's never really discussed.

It's not really 100% defined I guess - even the "Purebloods" are a bit of a ruse in modern times I think. In CoS Hagrid said something along the lines of 'there's not a witch or wizard today who's not Half-blood or less'. So I guess along the lines of Teresa's explanation makes sense there - once the line is 'tainted' by Muggle blood, it's no longer pure.
Then again, it's also likely that if you go down enough generations with Harry & Ginny's kids for example, it could very well be forgotten or the information erased that their great-great-great-great-great-great-great-great-great-grandmother was Muggleborn. It's highly likely that that even happened with some of the Pureblood families - the Muggle bloodline was absorbed and bred out to use a really icky term over X number of generations.
*shrugs*
It was a lot easier when I just thought of it in terms of "Half-blood" = Seamus Finnigan, one magical and one Muggle parent.

It's also been said, though, that after a certain amount of generations a family can technically "become" pureblood. I can't imagine how many though. >.>