Ok thanks! You learn something new every day! Has anyone tried this? And how much is sacrificed in egg color? I imagine that it may be somewhat unpredictable.Just crossing the 2 will not give you Sex Links. You have to use Barred Hens and solid roos to make sex links...... works like that with ALL breed of chickens. As for losing egg color when you introduce new blood to marans it will affect the genes for the egg color. Cuckoo typically are not as dark as a BCM so when you cross them you will lose egg color.... it just happens. When you breed related birds you egg color will improve when you breed from unrelated birds you have to kinda start over with egg color. From what I understand egg genetics are not understood and have not been studied much so beyond that I can't help you.