I tried the old wives tale method of choosing rounder eggs for hatch last year....It did not work. I had 96% hatch rate but 60% roo to 40% hen hatch outcome. And that was after waiting 2 wks after the roos were penned away from the hens before I started collecting eggs for hatching. I know that, in humans, the female carrier is heavier and can out live the male carrier. Meaning, if ovulation occurs soon after insemination more likely a boy, if later like up to 6 days later, a girl. Does anyone know if this would work with my hens? We raised laying stock last year and put nearly 57 roosters in the freezer. Yeah, well it's good to have enough chicken for a year but the work output to process those scrawny layer roo types is not worth the effort. I just can't imagine myself euthanising all the little cockrels at one day old...that is if I can even sex them correctly. Such a waste! But what do you do???