I recently hatched six golden neck d'Uccle chicks. All but one developed exactly the way a golden neck should. The one cockerel in question started developing feathers with the gold and creamy white.....but as time went on, he started to develop a beautiful blue in his wing and tail feathers. I've searched genetics, etc but cannot figure out how he became mostly golden/creamy white but with the blue as well. Would anyone here be able to tell me why or how this happened?