The Deathly Hallows Sporking Community

I figured the stuff in the book was DE-controlled Ministry propaganda, perhaps outright lies, just to give an excuse to whack Muggles and Muggleborns. But when JKR said in an interview that that was right, Muggleborns had to have Wizarding ancestry somewhere, then... ugh. That can't line up with the semi-randomness of it as already depicted.