Foreign diplomatic personnel stationed in the US sometimes have babies while in the US. These children get the same birth certificates as any other child born in the US, but they are not citizens. Ergo, a birth certificate is not proof of citizenship.
I’d be willing to bet that >99.999% of people with US birth certificates are citizens, but it most certainly is not 100%.
I’d be willing to bet that >99.999% of people with US birth certificates are citizens, but it most certainly is not 100%.