Perhaps he came to see himself as black because others saw him as black.
The eugenicist Madison Grant of New York wrote in his book, The Passing of the Great Race: "The cross between a white man and an Indian is an Indian; the cross between a white man and a Negro is a Negro; the cross between a white man and a Hindu is a Hindu; and the cross between any of the three European races and a Jew is a Jew."[3]
and
When the U.S. Supreme Court outlawed Virginia's ban on inter-racial marriage in Loving v. Virginia (1967), it declared Plecker's Virginia Racial Integrity Act and the one-drop rule unconstitutional.
What was the one drop rule?
The one-drop rule is a historical colloquial term in the United States for the social classification as black of individuals with any African ancestry.
“Perhaps he came to see himself as black because others saw him as black.”
Maybe I’m made of sterner stuff, or maybe he resents his mother for abandoning him as well. But if I was half-white and half-black, and my white family had cared for me and sent me to the best schools at considerable sacrifice, I think I would view myself as primarily white. Particularly if my black father had never done squat for me!
In any case, I would NOT consider myself to be totally black, as Obama claimed on his census form.