Why I believe people should not breed crested ducks.

[crazyfeathers]

Interesting, I didn't know about the defect. Why does it happen exactly? Thanks for your time and explanation.

 

[subhanalah]

Here is an article about it.
It happens due to a genetic deformity.

If two crested ducks mate, many of the ducklings will be so severely deformed, they die in their shell and never had a chance of hatching.
http://www.metzerfarms.com/Articles/CrestedDucksUnusualBrains.pdf