An individual born in the US is automatically a US natural citizen, UNLESS their parents were diplomats.
If they have no other connection to the United States except having been born here (i.e., neither parent was or became a U.S. citizen during their childhood) the citizenship they receive, if they receive any citizenship at all, can only be considered to have come to them via naturalization.
That is ridiculous. No wonder wealthy pregnant Chinese women come to US for holiday.
Pursuant to an uniform Rule of Naturalization?
Article I, Section 8, Clause 4:
[The Congress shall have Power . . . ] To establish an uniform Rule of Naturalization