I was wondering if Sumatra's are one of the breeds that carry a lethal gene. My breeding stalk is healthy I only incubate good quality eggs, never wait long then 7 days before the eggs go in the incubator. So far I have had 98% fertility rate, Every egg that is fertile full develops then the chicks seem to die in the shell with out piping. I keep my humidity at 45% during the first 18 days, and bump it up to 60% for the last 3 days. I keep the temp at a steady 99*F. I have broken open the eggs 6 days after the expected hatch rate. there are no deformities, none are under developed, they don't appear to have drowned or be facing the wrong way. So I was wondering if Sumatra's carry a lethal gene or not.