He could become a citizen of the U.K. But he is today a citizen of Indonesia. Indonesia would tell you that. Of course, Kenya might still hand him citizenship as well.
We can’t stop other countries from calling any of our Presidents citizens of their land. But we can question loyalties of our candidates. No one ever questioned his.
My conclusion about his Canadian birth was like solving a puzzle. It fit Occam’s razor and none of the other wild explanations of foreign birth were as simple and obvious as that one.
He does resemble his half brother(s) of Obama Sr, so I do think that was his daddy.
To become a citizen of Indonesia his parent(s) would have had to renounce any other citizenship. Indonesia did not then and may not now permit dual citizenship.
That's what the Natural Born Citizen clause was/is all about.