if he didn't grow up participating in his father's african heritage and culture, then he is as detached from his african roots as the majority of black americans are.
and a reason why many/most white people may not accept him as being partly one of them is because, at face value, he doesn't even look biracial (at least, not to me). he looks like a black man. and he's married to a darker-skinned black women, and they have two medium-dark skinned children.
i think if obama looked more like this guy, how white people personally identified
with him could
be different. this is totally conjecture, of course, because i've never ever asked a white person how they identify with people who are half black half white.