
I have a totally weird and random question. I just hope I can translate what's in my head into words...
Okay, imagine Draco Malfoy (definately a pureblood wizard) had a brother or sister who was nonmagic. That sibling would be a squib.
Now, imagine Lily's family. Assuming her parents were Muggles (which I don't really think they were, but that's beside the point), they gave birth to a magical child and a nonmagical child. Is Petunia, as the daughter of Muggles, a Muggle... Or is she, as the sibling of a witch, a squib?