Good idea Kathy! Or maybe even Holderread, since I know they don't mind answering genetics questions for people.
Since we are sort of on the topic of crests, if anyone is interested, take a look at t
his article which studied brain differences between crested and non-crested ducks. It looks like the reason it is so dangerous to yank on a crest (something a drake might do while mating) is because the fat and connective tissue the crest is made of is actually partially nourished by brain vessels coming directly from the brain to the crest, through the holes in the skull the crest sits over. It can lay fat deposits into the brain as well. So you can see how yanking something that is directly attached to the brain can cause a lot of issues.