Got it. Thanks.
I forgot the to specify the part that’s important.
“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. “
Obama’s mother was only 18. Some sources say the that “five of which after 16” is written as 14 in some lawbooks. Either way, at 18 she doesn’t qualify on her own to give Obama citizenship because his father was NOT a citizen. Had she had an American’s baby, it wouldn’t be a problem.