How many times have they laid? There is always an off chance that they have some kind of salmonella infection or something. It often causes infertile eggs, babies which die in the shell before hatching, or shortly after hatching. Sometimes the parents themselves don't show any signs or symptoms... they are just carriers of it.I dunno if they did for their first owner, but for me they have not. They almost hatched one last fall, but it died hatching because it was backwards in the egg.