The only way for O’Bama to not be a citizen is if his mother was married to his father and he was born outside of the US. If the mom was single and O’Bama were born outside of the US, O’Bama would obtain the same status as his mother-regardless of her age or time as a citizen.
Just so you know Obama has a past history of shunning even avoiding any position that would require him to pass a government examination of his and his family’s history.
As a part of the Harvard Law review he even turned down a chance to work as an intern that would surely have placed him at or with members of the Supreme Court thereby avoiding an in depth background check into his life, curiously he doesn’t need such a background check as president.