The Constitution does not, in words, say who shall be natural-born citizens. Resort must be had elsewhere to ascertain that. At common-law, with the nomenclature of which the framers of the Constitution were familiar, it was never doubted that all children born in a country of parents who were its citizens became themselves, upon their birth, citizens also. These were natives, or natural-born citizens, as distinguished from aliens or foreigners. Minor v. Happersett, 88 U.S. 162, 168.
This takes us to common law at time of the framing of the constitution for the definition. The history of English rulings at that time will make it clear what the the framers understood the meaning to be.