 And the former Broadway musical star and Grammy-winning R&B singer has revealed that famous R&B singers run deep in her family tree. It turns out that Stephanie Mills' real cousins are Casey and JoJo of the group Jodeci. Now, Casey and JoJo have other famous singing cousins as well. Take, for instance, Dave Hollister, who once sang lead vocals for the R&B group Blackstreet.