This (seems to be) incorrect.

(EDIT: It looks like I have not understood. Discussion should continue, as opinions are divided, but the issue does indeed appear to clinched by having two citizen parents (or a father who was a citizen, in which case the mother may well also be a citizen under common law 'coverture') rather than where one is born. Leaving my original comment here, for the discussion, but I think I was incorrect.)

There are potentially several paths to becoming a "natural born citizen". The main one is being born in the United States and not requiring any other naturalization process to become a citizen.

Apparently, there is some uncertainty whether someone born outside of the US jurisdiction but of one or two American citizen parent(s) and is a citizen at birth qualifies as "natural born citizen".

https://www.law.cornell.edu/wex/natural_born_citizen

A natural born citizen refers to someone who was a U.S. citizen at birth, and did not need to go through a naturalization proceeding later in life. Under the 14th Amendment's Naturalization Clause and the Supreme Court case of United States v. Wong Kim Ark, 169 US. 649, anyone born on U.S. soil and subject to its jurisdiction is a natural born citizen, regardless of parental citizenship.

In Harris' case, she needs the certificate that she was born on US soil (under US jurisdiction), because neither of her parents was a US citizen when she was born.

The Constitution does not expressly define “natural born” nor has the Supreme Court ever ruled precisely upon its meaning. There is some uncertainty over whether a person that is born outside the U.S. but still becomes a citizen at birth through a statute is a natural born citizen. One example is U.S. citizenship that immediately passes from the person's parents.

(also https://www.law.cornell.edu/wex/natural_born_citizen)