There is more also.. I don’t have it close by, but basically, a law right before he was born stated that the parent isn’t considered a citizen (for purposes of this) if she hasn’t lived in the US for at least 4 years after her 16th birthday, being that she was 17, if he was born in Kenya, as his grandmother implied, even her citizenship wouldn’t cover him. IF true..
Yeah there is. You are thinking of the Immigration and Nationality Act of 1952. Section 1401 ( http://www.fourmilab.ch/uscode/8usc/www/t8-12-III-I-1401.html for full text concerning citizenship at birth) Ill let you read it all as there are several circumstances listed and I would effectively just copy and paste them here. However, nothing in the text pertains to natural born status which is required by the Constitution.
So as I said above the 1970 law is the only one I can find that deals with natural born status.