Just because someones mother is an American citizen, that doesn't automatically mean their offspring are. There are laws governing that, and this is precisely the issue with Obama.
Actually, I think the current interpretation of the constitution is just that...if your mother is a citizen at time of your birth, then you are a natural born citizen. But when obama was born, they were more strict about who they gave “natural born” status too.
I could be wrong though.
I think you’ll have to take that up with the Supremes.