I have this theory- and it's just a pure guess, if a d'uccle (Mille or porcelain) has more dark on its beak, does that mean it's a boy? I've noticed my adult porcelain d'uccles have mostly dark beaks on the males, and more yellow/horn on the girls. And I'm guessing, if their feet are mostly pink, they are a girl, and mostly yellow they are a boy? I also wonder if the spot on their head or absence of one has a significance or not.... Anyone have experience with this?