One thing that I've thought of is that the "derp" gene has to be recessive. If there was anything noticeably wrong with the two parents of Derp and Susie, they wouldn't be bred. So, even if you bred a derp chicken, the effects might not appear in that generation; but later down the line it...
Flora, our Blue andalusian, is not using the nest box. Instead she insists upon laying her eggs in secret nests in corners of our garage. How can we get her to stop? Every time we find one there is like 10 eggs in it.