Bloodlines (and a small spoiler)

[callie603]

No: HPFGUIDX 66853

Please forgive me if this theory has been brought up before, and 
please direct me to where I can find the discussion. I tried 
searching but I guess I didn't get the right search term because it 
was still too many responses to wade through.

Has anyone thought that maybe being a pure-blood depends on the 
mother only? For example, Voldemort is not considered a "mudblood" or 
a half-blood because his mother is a witch, not his father. He would 
not be trying to kill all the mudbloods and be the heir of Slytherin 
if he were one (who detested them). Likewise, Lily is considered a 
mudblood, and thus Harry is often reminded that he is not pure blood 
even though both his parents were wizards. So perhaps his father's 
family were all wizards but it doesn't matter because his mother was 
not pure blood. And if Lily's mom was not a witch (either a squib or 
a muggle) but her father was a wizard, then she would still be 
considered a mudblood because of her mother. Then they would be very 
proud of Lily for getting her Hogwarts letter and maybe disappointed 
that Petunia either turned out to be a squib or a bad witch. 

In any case, does anyone else have trouble reconciling how the 
characters categorize people as pure bloods or mudbloods--it doesn't 
seem to make sense. Voldemort is Slytherin's heir, who hated 
mudbloods, and he is himself one. Harry is always reminded that he is 
not pure blood yet his parents were both wizards. Due to the 
importance that mother's blood has played in OoP (that Harry's 
protection under the Dursley's is ancient magic and has to do with 
his mother's sacrifice and the fact that his mother's blood lives in 
Petunia), I think this could be a possible explanation for the 
apparent inconsistency. Any thoughts? Please tell me if this topic 
has been hashed to death already. Thanks. :)

callie603