Yellow shanks are recessive to pinkish/white shanks, so, assuming your hens are pure and do not carry a yellow shank gene, you should get all pinkish-legged offspring, all carrying the gene for yellow shanks. The problem lies in that then you then have birds with a recessive gene that will pop back up in future generations, and since it is a recessive gene and thus birds can be carrying it without you knowing until suddenly their offspring have that recessive trait, it's a whole lot of trouble to breed that out of a line. If you're just breeding them for fun and don't plan to sell them as pure Buff Orpingtons, then that's not really a problem. But, if you do want to breed and sell pure Buff Orpingtons, you should consider replacing your male with a pure Buff Orpington male instead.
