USA, Canada /
Dual citizenship - US doesn't care if you don't give up Polish passport [103]
When they turn 18 they're supposed to chose one citizenship.
That's a myth.
You're correct convex and since the US is the only country I know of where you get citizenship by simply being born on our soil (are there other countries that do the same?
Lots of countries do (or did).
However, nowadays dual, sometimes triple or more citizenships are pretty common. Case in point, a friend who's born in Zimbabwe, raised in South Africa, educated in the UK and now lives in the US. I know for a fact she has a South African passport, a British and a US passport. Not sure about if she has a Zimbabwe passport too.
That's what I was getting at earlier. Allegiance to a single country doesn't mean much anymore in this globalized world.