Genes are funny things. I've seen some biracial (1/2 black/1/2 white) people that are similar to Obama in color and featurewise. I've seen some that look less black than I do as a "quadroon." I've seen many quads that look obviously black, some look very Caucasion, like Victoria Rowell's daughter. I've been told I don't know how many times that I look Greek. I have no idea what Greeks look like. ME, I guess! Black people almost always know that I have black in me. I've gone to identifying as black partly for that reason.