Ok, I have a pen of 2 frizzle roosters, and a bunch of non related smooth coat frizzles and silkie hens. I get a high rate of frizzle babies. BUT, the female chicks all seem to 'fail to thrive'. They are in the same brooder, same food, same age, but they never get out of the fluff stage. They grow enough wing feathers to show me they are frizzle, then they stop eating, start lingering, and eventually lay down and die!! There are no parasites, I checked. (small swipe with Ivermectin under wing to be sure) Not being bullied or crowded. (only 6 chicks in one brooder, 5 in the other) They come in from the coop the day they hatch, its too cold for the hens to raise em, but I let them sit on them if they want. I have been raising chicks for years, and these pens have produced countless frizzle babies, but they always seem to be roos.... Has anyone ever heard of a lethal gene being linked to sex? I know it can be linked to color, but these babies are all different colors. I am stumped.... Anyone have any ideas? Thanks!