Why roosters only?

[Hysteria]

My native tongue is Hungarian; living and serving in Japan as a Christian missionary and pastor.
My “English” is terrible I know.
Thanks for your kind correction.

 

[Yard Farmer]

The sex of baby chicks is decided by the mother hen in her ovum, and is unaffected by sperm. Totally different from humans. So temperature won't affect gender. I doubt egg shape makes any difference either, but I can't state that as a fact, just a suspicion. So basically it is down to what the hen's body chooses, and there is no way to change it. Some hens may produce more male offspring than others. I'm not sure of that, either. But more likely it is just pure chance, and you've had bad luck. Maybe try hatching eggs from different hens next time, or buying sexed chicks from TSC or a hatchery.

I 2nd this.

I've hatched eggs from a AC's before and I had one throw almost all girls from the eggs I hatched from her, I hatch at least 30 chicks from this particular hen and only got 1 boy, and he was one I had sold.