If Obama was indeed born in Kenya, which I doubt, he would stll seem to be covered by this:
"Any one born outside the United States, if one parent is an alien and as long as the other parent is a citizen of the U.S. who lived in the U.S. for at least five years (with military and diplomatic service included in this time) ... Anyone falling into these categories is considered natural-born, and is eligible to run for President or Vice President. These provisions allow the children of military families to be considered natural-born, for example.
Those 5 years have to be over the age 16. His mother was 18 when she had him.
I am fairly certain Obama was born in Kenya. (Say 90%) There is a lot of evidence of this the primary one is not allowing any one to see the original COLB which has a Place of Birth line on it. (Also his African grandma said so).
According to the law in the books between 1952-1986...
If only one parent was a U.S. citizen at the time of your birth, that parent must have resided in the United States for at least ten years, at least five of which had to be after the age of 16.
She was 18 when she had Obama.