Wizards with families split between Muggles and wizards are referred to as half-bloods. Due to the dominance of the magic gene, children born to at least one magical parent will usually be magical themselves, meaning that a non-magical child born to a Muggle and a wizard is considered a Squib, not a Muggle[3]; the term 'half-blood' is misleading in that it does not necessarily imply a half-and-half split in wizarding/Muggle ancestry, but rather any sort of 'impurity' up to two generations back. By the 1990s, most of the magical population were half-bloods.
The ancestry of a half-blood can be:
* One pure- or half-blood parent, one Muggle parent — e.g. Lord Voldemort, Severus Snape, Dean Thomas, Seamus Finnigan
* One pure- or half-blood parent, one Muggle-born parent — e.g. Harry Potter, Nymphadora Tonks, Albus Dumbledore
* Two magical parents, known Muggle ancestry — e.g. Ted Lupin, James Sirius Potter, Albus Severus Potter, Lily Luna Potter