The Constitution does not define the term natural-born citizen. The 14th Amendment does not define the term natural-born citizen and it does not designate anyone as a natural-born citizen.
The only group of citizens clearly and undoubtedly understood to be natural-born citizens are those persons born on U.S. soil to two U.S. citizen parents. With its opinion in Wong Kim Ark, the SCOTUS left unresolved the natural-born status of all other citizens. There is no settled law on the matter. Barack Obama, as a self-proclaimed Constitutional Law professor, knows this.
Then I’m not a “natural-born” citizen. My father was a US citizen, and my mother was a war bride who had been in the US for sixteen years and had resident alien status (she was, and remained all her life, a Canadian citizen) when I was born. Therefore, I wouldn’t be eligible to serve as President. Interesting.