He's also cuckoo, just can't see it due to his being white- we know he is cuckoo because his mother was & it's sex linked(white pullet does not have cuckoo for the same reason).
Cuckoo/barring also has the side effect of interfering with pigmentation in the dermal layer in the leg skin.
Another possibility is a gene called Id- Inhibitor of Dermal melanin. It's also sex linked and inherits the same way as cuckoo/barring does. it's possible for the boys to have both Id and cuckoo resulting in very clear legs.
A white skinned bird with cuckoo and/or Id will have white legs... a white skinned bird lacking Id or cuckoo will have blue legs. It's yellow & green legs, on yellow skinned birds, respectively.
for dominant white to be a possibility, it's necessary for at least one of the parents to have it, just like with the NN gene. So with a gold laced roo, cuckoo hen, that's simply not possible.
