Before I got rid of my eggs I wanted to try and figure out what went wrong with my Japanese bantams......so I opened the egg and found the something was wrong with their beaks they were deformed any one had anything like that....I'm thinking that's probably why they couldn't hatch.....everything else looked fine but I've never seen our chicks before like this that we hatched I will post a picture later if any one wants to see it.
I would guess its part of the lethal gene that makes them not develop properly.