[RummyChick]

You can start here. SCOTUS case that discusses this aspect for a 1969 birth.

http://www.law.cornell.edu/supct/html/99-2071.ZS.html

[MtnClimber]

That case seems to indicate that it is different if the unwed father is the US citizen than if the unwed mother is the US citizen. In Baraks case the unwed mother being a US citizen would be in his favor.

I have always wondered about his Indonesian citizenship after he was adopted by his step father. Indonesia does not permit dual citizenship so he would have had to renounce his citizenship. Would that cause issues?