The US Supreme Court referencing and quoting Vattel..”Vattel...natural born citizens are born to citizen parents”..heck they gave chapter and page number.
from the Supreme Court..an excerpt..
“Thus Vattel, in the preliminary chapter to his Treatise on the Law of Nations, says:.....
“The citizens are the members of the civil society; bound to this society by certain duties, and subject to its authority; they equally participate in its advantages.
The natives, or natural-born citizens, are those born in the country, of parents who are citizens. As society cannot perpetuate itself otherwise than by the children of the citizens, those children naturally follow the condition of their parents, and succeed to all their rights.”
Again: “I say, to be of the country, it is necessary to be born of a person who is a citizen; for if he be born there of a foreigner, it will be only the place of his birth, and not his country. The inhabitants, as distinguished from citizens, are foreigners who are permitted to settle and stay in the country.” (Vattel, Book 1, cap. 19, p. 101.)”