His father was a foreign national making him a British subject and Kenyan national at birth, Obama even admitted it on his website.
A natural born citizen is NATURALLY a citizen because they could not be anything else and have only ONE nationality.
Anyone born with split nationalities is PRECISELY who the founders were excluding.
http://www.art2superpac.com/issues.html
Dual citizenship is not illegal in the US.
I personally know a man who is a dual citizen of the US and Taiwan. His parents are both green card holders, though not US citizens. He became a US citizen by being born on US soil.
“U.S. law does not mention dual nationality or require a person to choose one nationality or another. “ Nothing about dual citizens being ineligible for President.