One only needs to be born a U.S. citizen rather than have to be naturalized as a citizen.
That has always been the rule as the Constitution only mentioned or envisioned THREE types of U.S. citizen.
One type were those who were citizens at the time of the adoption of the Constitution. They are all dead.
Currently there are only TWO types of U.S. citizen - those who were born U.S. citizens and those who had to be naturalized as citizens.
Being a natural born citizen used to require having both parents be US citizens.
That’s a nice spin for the pro-Rubio, Jindal, Cruz types, but it is at least open to debate, considering that the language used in the Constitution for only issue of the presidency fits with the higher standard that the term was commonly known to mean at the time.