What Percentage Makes Someone a Half-blood?

Question

I was checking on something in the Harry Potter wiki and saw Harry listed as "Half-Blood." Both his parents were magical, but, as we know, his grandparents on his Mother's side were muggles. This reminds me of the racially loaded terms like octoroon. (In the south, you still hear those terms every once in a while.) When there was still segregation, having only 1 great-grandparent of an ethnic group was enough to classify a person of that group.

So how far down the line did it go in the Harry Potter universe? Just how many generations removed from a muggle-born would a person have to be before they're no longer classified as half-blood or something similar?

Answer 1

As per J.K. Rowling herself:

Why are some people in the wizarding world (e.g., Harry) called 'half-blood' even though both their parents were magical?

The expressions 'pure-blood', 'half-blood' and 'Muggle-born' have been coined by people to whom these distinctions matter, and express their originators' prejudices. As far as somebody like Lucius Malfoy is concerned, for instance, a Muggle-born is as 'bad' as a Muggle. Therefore Harry would be considered only 'half' wizard, because of his mother's grandparents.

If you think this is far-fetched, look at some of the real charts the Nazis used to show what constituted 'Aryan' or 'Jewish' blood. I saw one in the Holocaust Museum in Washington when I had already devised the 'pure-blood', 'half-blood' and 'Muggle-born' definitions, and was chilled to see that the Nazis used precisely the same warped logic as the Death Eaters. A single Jewish grandparent 'polluted' the blood, according to their propaganda.

Therefore, as per JKR, the official Third Reich formula-like rules were in effect:

In Germany itself, the Ahnenpass and Nuremberg Laws classified people as Jews if they descended from three or four Jewish grandparents. A person with one or two Jewish grandparents was a Mischling, a crossbreed, of "mixed blood". (source)

Of course, as usual, the bosses got to make any exceptions they wanted - e.g. Voldemort was certainly not considered "half-blood inferior" by his own rules. Same as with Nazis - quoting my completely unrelated answer on Skeptics.SE:

These events (Erhard Milch being issued a German Blood Certificate) prompted Hermann Göring to say famously "Wer Jude ist, bestimme ich" ("I decide who is a Jew")

Answer 2

You see in the 7th book that people need to "prove" their ancestry goes back far enough. This does suggest that if you had a muggle ancestor "enough" generations before you, it doesn't count anymore. Also, I think that pure blooded families that can trace their ancestry hundreds of years are quite rare, and I think this because of how disappointed Death Eater pure blooded people are (ie Malfoys and Blacks) in the Weasleys (and all three families can trace their pure blooded lineage for hundreds of years). I would guess if many families were pure blooded (and could prove it), then the Weasleys would just be disliked or shunned, and not actively disappointed at.

Answer 3

I suspect that your racial connection is appropriate, as half-blood was a "racist" term. Meaning that someone with less magic blood than you have could be termed half-blood.

In-universe, I am not sure we have enough of the history through 3-4-5 generations to really answer. It does seem to be said in contradiction to the few long-lived, pure-blooded houses, who can trace their ancestory back for centuries. Against this, anyone with muggle-blood - or who cannot trace back properly through this time - is in danger of being termed half-blood.

Answer 4

I think anybody that has non-magical blood in their ancestors is termed 'half-blood' as this refers to anybody that is not 100% magical.

However, I'm sure that there was a time that the first magical people came into being, would they then be considered half-blood? Unfortunately that sort of question could never be answered...