The hen determines the gender of the egg for chickens so it looks like you are on the right track documenting which hen produced more female chicks.
Interesting.
Do these traits pass on from hen to chick? and Are there other factors? We hatched out 9 chicks from 13 shipped eggs & only two were male. Could that breeder have done something to increase her odds of females? (ie - changing hens' diet or in my case, stop using Omelet's mom for hatching eggs since she has more male offspring) Could I be doing something during the incubation to make it harder for males - but not females - to hatch?