I was born in England to American parents, and held dual citizenship until my formal oath of citizenship before a judge at age 18. The FACT of that oath is attested by the Certificate Of Citizenship issued to me at that time. It indicates that my citizenship is derivative from my parents, which does make me “natural-born” - and thus better qualified to be President than Obama.
Depending on when you were born, you don’t even need to take an oath.
My youngest Daughter was born in Germany, and all we had to do was fill out a form and send it in. And we did that 3 years after she was born. Another thing, if the Mother had a passport with a picture of her and the child, that was also acceptable as proof of citizenship.
0bama has provided none of these things we’ve mentioned.