Obama is 13th generation American on his mother’s side. I suspect that none of the idiots claiming falsely that he was born in Kenya are.
Besides, because his mother was unquestionably a US citizen at the time of his birth, he is a natural born US citizen inheriting from his mother. Just as John McCain was born outside the US but is a natural born US citizen inheriting from his parents. And just as Mitt Romney’s father was born outside the US but was a natural born citizen inheriting from HIS parents.