↑FAQ at テンプレート:JKRS - "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."
↑ 2.02.1『ハリー・ポッターと秘密の部屋』第7章 穢れた血と幽かな声 - Ron: "Most wizards these days are half-blood any-way. If we hadn’t married Muggles we’d’ve died out.”"
↑ 4.04.1Writing by J.K. Rowling: "The Malfoy Family" - Pottermore - "From the imposition of the Statute of Secrecy onwards, no Malfoy has married a Muggle or Muggle-born. The family has, however, eschewed the somewhat dangerous practise of inter-marrying within such a small pool of pure-bloods that they become enfeebled or unstable, unlike a small minority of fanatic families such as the Gaunts and Lestranges, and many a half-blood appears on the Malfoy family tree."
↑『ハリー・ポッターと謎のプリンス』第10章 ゴーントの家 - Marvolo Gaunt: "Centuries it’s been in our family, that’s how far back we go, and pure-blood all the way!"
↑『ハリー・ポッターと謎のプリンス』第12章 シルバーとオパール - " "“The Death Eaters can’t all be pure-blood, there aren’t enough pure-blood wizards left,” said Hermione stubbornly. “I expect most of them are half-bloods pretending to be pure. It’s only Muggle-borns they hate, they’d be quite happy to let you and Ron join up.”""
↑『ハリー・ポッターと死の秘宝』第29章 失われた髪飾り - Neville: "They don’t want to spill too much pure blood, so they’ll torture us a bit if we’re mouthy but they won’t actually kill us."
↑『ハリー・ポッターと死の秘宝』第13章 マグル生まれ登録委員会 - "“No, no, I’m half-blood, I’m half-blood, I tell you! My father was a wizard, he was, look him up, Arkie Alderton, he’s a well-known broomstick designer, look him up, I tell you — get your hands off me, get your hands off —”"
↑See this image of Porpentina Goldstein's MACUSA identification card on display as part of a prop exhibition in Japan. Both of their parents died of Dragon Pox, showing that they were wizards, which means that their Muggle heritage was more distant.