Excuse me, some buff lines carry dominant white. (just now noticed Pyxis already covered this, my apologies for repeating)
Not entirely unreasonable for this chick to be a dominant white with the light down and feathers on what could have been a black downed chick.
by the way the chick is probably a pullet as orpingtons have a sex linked gene that makes their legs white. It also has a negative effect on black skin. In theory, cockerels would have either normal looking skin or nearly so with either really pale gray or patchy skin with the pullets being visibly darker but then the black skin expression varies so wildly nothing black or white could be said about it, ha...
Edited by Kev - 10/7/15 at 2:56pm