Can I say that many people play up to their stereotype? Everyone likes to be part of a larger group and they often affect the diction, speech pattern and vocabulary of the group they associate with.
Hell, Eminen and Vanilla Ice "sound" black. That would be the black stereotype as imagined by suburban white youth. My Chinese/Black Jamaican friend sounds British and was educated in private schools there.
I guess it all depends on how much TV you watch and whether your parents forced you to go to cotillion and take diction classes.