I don't believe anyone now saying that natural born citizen means two citizen parents was taught this in school. I'm not calling anyone a liar, I just think that their memory is heavily influenced by the strong beliefs they've formed relatively recently.
Memory is a funny thing, but I have seen evidence that any such argument, one that supposedly was learned in school, was somehow mysteriously rare as hen’s teeth in threads discussing eligibility until AFTER the 2008 election.
Why do you suppose that is?