Nein. B/C if she had such accuracy, wouldn't she only have hatched a single cockerel every year? Your question is an interesting one, which most likely does not have an answer and would be the subject of an other study. It is the hen who determines the gender of the egg. And, some hens are more likely to produce pullets, while some other hens are more likely to produce cockerels. So, perhaps those hens who produce cockerels lay pointy eggs??? So, if a flock owner happens to notice a particular hen who seems to produce more pullets, that flock owner SHOULD make every effort to hatch that hen's eggs, and use her daughters for future breeders.
Then, there is the whole temperature issue. Incubation temp can be tweaked to favor production of pullets. However, when tweaking temp, all that is really happening is that the weaker male embryos are being killed off in early development. So, the hatch rate goes down, but pullet % goes up. Some flock owners also note that pullet to cockerel ratio changes according to the temperature when eggs are collected.
They do all look the same with the white spot on their backs like the boy in the photo. On the webpage the pullet chick doesn't seem to have that spot. You will try again won't you?
