If you were born abroad but your parents are U.S. citizens, then most probably you can apply to be a U.S. citizen. If only one of your parents was a U.S. citizen at the time then maybe either you “acquired” U.S. citizenship at birth through a parent, or you “derived” U.S. citizenship as a minor through your parent(s). If the child is born outside the U.S. but one of the parent naturalizes and the child is residing with that parent in the U.S. and is unmarried and below 18 years of age, then such child may apply for his citizenship by filing Form N-600.
If the child resides outside the U.S. or the child has been adopted by a U.S. citizen parent, then Section 322 of the Immigration and Nationality Act will be applicable. Form N-600K must be filed at the U.S. Consulate/Embassy. Proof of the child’s parent’s citizenship and is physically present in the U.S. The child must be below the 18 years of age and is in legal and physical custody of the applicant.