Can anyone shed some light/advice on this? I've had 4 hatches this year, all pretty dismal, like 10%, though the birds that do hatch are very healthy and strong and grow into strong healthy adults... only... they are almost ALL roosters! My incubator is a top hatch brower model from about 15 years ago, so it may be an air circulation problem, as I gave some eggs to a someone and she hatched 16/24, though not sure the %age of roos. Could it be the daddy rooster? Or the incubator is crap and only the very strongest chicks hatch, and that happens to be roos? I have had 2 hens out of almost 20 hatchlings. Help!