[Maritime Q-Scout]

From what I understand if you gain US citizenship you must renounce your previous citizenship.

However what's interesting, and is the case here, is what happens when there is no previous citizenship?

Cruz wasn't a Canadian first. He was born an American, as his parent was American. However, he was born Canadian as he was born in Canada.

The underlying issue is a baby doesn't have capacity to renounce citizenship, and the logistics to keep track of the small percentage of people that fall into this exception wouldn't be cost effective to monitor. So really it isn't a problem until you try and run for president, despite being born on US soil or to two US citizens is a foolish rule.