[philman_36]

I think for both of them mummy was one when they were born.

Mummy was a US citizen and Daddy was an alien, right?
The children of such unions need a law to make them US citizens, don't they?

[discostu]

Only in so far as EVERYBODY needs a law to make them a citizen since citizenship is defined by laws. But the most common set of laws on this, and what we have here, is that if one of your parents is a citizen when you’re born so are you.

[DiogenesLamp]

Mummy was a US citizen and Daddy was an alien, right? The children of such unions need a law to make them US citizens, don't they?

Yes, it's called the "Cable Act" of 1922. Funny thing. For the first 146 years of the nation's existence, we didn't have such a law.

Were none of those children born in such circumstances prior to 1922 "natural born citizens"? And then suddenly after 1922 they were?