American blacks who are on average about 12% white and 5% native. The obsession with discussing how black black people are is annoying. Slavery, Jim Crow, and racial discrimination wasn't and isn't exclusively for 100% sub-Saharan African descended people; only South African apartheid micromanaged that much.

edit: And 50% is a microscopic amount, now?

I knew a colleague who had a relative who knew Obama before he became a politician. Back then, Barack was far more embracing of himself as a mixed-race individual. He made a choice later on to be identified as a black man.

Another interpretation is that the choice was made for him.