I'm having someone hatch out a few of my duck eggs.. I have 2 crested drakes...and 4 non crested hens. So far he's had 5 ducklings hatch..and none are crested. Why is this? isnt the crested gene dominant? I dont have any crested hens on purpose because i heard if you breed 2 crested together that it can be fatal... is this true? thanks!