It’s natural law. It doesn’t need any stinking statute or definition.
“A person born in a nation of citizen parents.” (Jus solis + jus sanguinis.)
It is natural law - period. Simple and logical.
No, it is not as simple as that. It is jus sanguinis or jus solis. Birthright citizenship is the law of the land and children born abroad to American citizen (s) can automatically acquire US citizenship. I know that as a fact professionally and personally.