I went to high school with two black sisters. Both very pretty girls and I think their father was some form of military. One day I overheard one of them explain to a white girl that they never could associate with other blacks because they where always being ostracized for "acting white". Both were dating white guys. She lamented that they were expected by other blacks to act a certain way in order to be accepted.
It's not solely a race issue. It's a cultural issue too. The ghetto culture acts like crabs in a bucket and tears down anyone that tries to rise out of it. They associate success and decency with "whiteness" and whiteness is always negative in their view. It's the old "house ninja" stigma.
