I've hatched refrigerated eggs that were about 2 weeks old and long skinny eggs at 50/50 gender(someone said they'd all be males).
Unlike some reptiles, gender in chickens is determined at fertilization not by outside or incubation temps...
**Although this might not be 100% absolute as there is a point during incubation where the sex of the embryo could potentially be flipped, but we have not figured out if this is possible or probable to any degree...
*I* knew that....some newbie spouted it at the time I happened to have just set the long eggs, was kind of funny.
Yeah, I figured you did but there is no shortage of people that still believe otherwise based on wives' tales or hearsay... And there is are still people getting funding to do try and find that unlikely to be found sex trigger that could revolutionize the poultry industry...