[Red Badger]

If Woodrow Wilson’s mother was a Brit, how could he become POTUS?.............................

[Verginius Rufus]

Wilson's father was born in the US. His mother came to the US as a child. (That Wilson considered himself a citizen of the Confederate States of America for several years apparently did not bother anyone--he was a minor at the time anyway.) President Arthur's father was an immigrant.

Wilson became POTUS only because Theodore Roosevelt ran as a third-party candidate.

[ccmay]

If Woodrow Wilson’s mother was a Brit, how could he become POTUS?

Same as any of the others: by right of being a citizen at his birth, instead of naturalized at a later date.

I.E. born on American soil, no matter the nationality of his parents, or born overseas to at least one parent who is an American citizen.

There are deluded people who claim your parents or even grandparents need to have been citizens for you to be considered a native born citizen, but they are quite wrong.