ALL my favorite singers are black and as a musician I've often pondered just what does make the difference.
I think its more cultural factors than anything. When you consider the prominent role music has played in black culture throughout its history as well as the soulful direction it has taken. (Even black church is a musical celebration). Any kid growing up exposed to such an abundance of heartfelt soulful singing is bound to be naturally influenced by it.
Next, as strange as it may sound, I think black dialect is a huge factor. I'm not much of a singer and dont know all the proper techniques, but I did once hear from a singer in training that most peoples normal speaking voice is the exact OPPOSITE of what your body needs to be doing to sing good because speech constricts vocal cords and doesnt generally come from the diaphram. Based on that, theres something about black speaking dialect that just seems much more smooth, relaxed, and free flowing than other dialects. It would stand to reason that something about it might also be helpful (or at least less restrictive) to proper singing technique.
Then again, maybe white men just cant sing, dance or jump, and I should just stick to guitar playing. LOL!
But seriously, what do you properly TRAINED singers out there think about the dialect factor?