thats where you are wrong...if Obama was born in Kenya he is a Kenyan citizen. US law stated that in order for him to be a US citizen his mother had to be 19 at his time of birth. She was only 18 when Obama was born. Kenya law stated that if one parent was a Kenyen citizen then the child was automatically a Kenyan citizen. Obama’s father was from Kenya. Additionally, Obamas mothers 2nd husband was from Indonesia, he adopted Obama and they lived there for several years. Obama went to private school in Indonesia and his mother listed his religon as Islam on his school records all this would make him an Indonesian citizen. So tecnically he has dual-citizenship with Kenya and Indonesia...and none with the US.
That's a big if, considering all of the evidence points to Obama being born in Hawaii.