Sirius a "pureblood"?

[flower_fairy12]

No: HPFGUIDX 37217

I had always just assumed that Sirius was from a pureblood family, 
because he doesn't act like he would come from a muggle one, because 
he knows so much. Well, obviously Harry doesn't know because he has 
never been told, he still explained what a PlayStation was and Sirius 
could have known full well what one was (maybe the dementors liked to 
play on one in their spare time. It could happen!!!)

Or, even if he doesn't it is most likely that he is half-blood. It 
would add a balance.

Rosie