There were/are a good number of FReepers who agree with Grayson on this and they feel the same way about Obama.
As a former Army brat I have always believed if you are born to an American parent no matter where you are in the world you are a U.S. citizen.
The only place the Constitution specifies “natural born citizen” is for POTUS. It grants that “a citizen” can be a U.S. Representatives/Congressman, a Senator, an Attorney General, Secretary of State, or Supreme Court Justice.
The argument arises as to the meaning of “natural born,” which our SCOTUS has yet to define. Attorneys can and do argue the point to death. In the strictest interpretation, however, children born outside of the country to citizens in the service of the country are “natural born.”
Jus sanguinis (Latin: right of blood) is a principle of nationality law by which citizenship is not determined by place of birth but by having one or both parents who are citizens of the state. Jus soli (Latin: right of soil) is a declaration that the citizenship is determined by the place of birth. Many nations have a mixture of jus sanguinis and jus soli, including the United States, Canada, Israel, Greece, Ireland, and recently Germany.
To reconcile this obvious conflict, technically a person could hold dual citizenship, by place of birth, and by nationality of one or both parents.