[conservativejoy]

If the framers of the Constitution had wanted to use Vattel's definition they certainly could have, but they didn't and instead defined a natural born citizen quite differently in 1790. The same men who framed the Constitution said this:

The Act also establishes the United States citizenship of certain children of citizens, born abroad, without the need for naturalization: "the children of citizens of the United States that may be born beyond Sea, or out of the limits of the United States, shall be considered as natural born Citizens".

This act was indeed superceded by subsequent acts in 1795 and 1802 and many others up until today, but I think the framers thought they had defined natural born citizen sufficiently to not have to repeat it in every law.

[Mollypitcher1]

“the children of citizens of the United States

Citizens is plural .....