I think a lot of black people are ashamed of the blues genre because they perceive it to be connected to slavery. Most of the black blues musicians are 'mature'...not too many young black musicians are taking up the blues tradition. The only one that immediately comes to mind for me is Robert Cray (and he's not that young), and he plays a 'respectable, uptown' classy style of blues, IMO; no one younger and black is trying to play a more traditional style of blues. Those who pursue the raw, emotional style of blues are liable to be white, because they harbor no negative connotations of slavery in the music. They are drawn to it because of the emotional power it conveys.

Just guessin'