Is Obama black or white?

Someone asked me “How can we say Obama is black?”
I curiously asked “What do you mean by that?”
“Well one of his parents are black and one is white so he’s equally white as he is black”
I replied and said “How do you know one of his parents are black and one is white?” He said “I’ve seen them.”

What I was getting at is if you define someone’s race as the races of their parents, then you have to define their parents race off the race of their parents and so on and so on.