What I've been told is the seramas have a diluted version of the short leg gene found in japs. This does cause 25% fatality in japs but the fatality should be less in seramas. It also causes death more toward the end of incubation not in the first week. I've got my 2nd batch of eggs from seramasun in texas and so far out of the 16 eggs I've set from them I've only lost 1 in the first week and 1 on day 10 this time. Last time a humidity issue caused me to only hatch 2 despite 6 of 8 making it to day 17. Right now I have 7 of 8 eggs still alive.