"Admission" is the wrong word. Zero's African blood has always been a central plank of his "legend" (as it's called in tradecraft). It made him a millionaire and catapulted him into the White House. Here he was proclaiming his African heritage before a national audience in 2004:
https://www.youtube.com/watch?v=L5V2U6IJSYc&t=8m5s
Of course, it's conceivable he came by his black genes through another route, e.g., FMD or Malcolm X. But it's extremely unlikely. Nor is it of much relevance. He believes the Kenyan anti-colonial commie BHO, Sr. to be his daddy and the source of his dreams (no doubt heavily interpreted early on by FMD), and that's made him what he is: our first anti-American president.
Nor is it of much relevance.
Only to people who have no interest in truth or the restoration of what the US was supposed to be.