system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If the British monarch had a child while visiting the states, and then fulfilled all the requirements, could that child grow up to be President and the King/Queen of England?
gpt
If a British monarch were to give birth abroad, they would most likely have declared whatever place she was to give birth in as part of "international territory". By doing so, the baby would be granted whatever citizenship the mother had.

This happened in Canada for the birth of Princess Margaret of the Netherlands. The birthing ward of the Ottawa Civic Hospital was "declared to be officially a temporary part of international territory, so that she would be born in no country and would inherit only her Dutch citizenship from her mother". This is also why there is now a tulip festival in Ottawa every year - the Dutch Royal family sends the bulbs to Canada every year in recognition of it.

TL,DR: Any place in the world can be declared international territory in order to avoid these problems.