One thing that no one is taling about is that when a child is born to parents of different races, the child is usually ascribed the race of the birth mother.
That would mean that Obama is not black.
The American tradition was the “one drop rule” by which someone with any African ancestors would be considered Black. Homer Plessy, of the famous Plessy v. Ferguson case, was one-eighth Black, but the Supreme Court found him to be a Negro and thus could be legally excluded from white accommodations.
One drop may be a tradition; but it is not a federally qualifying standard.