You can say that Ronott, and I would agree with you. It sounds pretty stupid. But, I can't disagree with my last 3 hatch results compared to the previous 2 hatches. And, since the proof is in my numbers, I will continue to work with this myth that has worked for me thus far. On a hatch of 10 birds, I'll gladly take 6 or 7 pullets instead of 4. Thanks! Of course, it depends on which study you read. I read a study, and the results of it were minimally positive in swaying the gender towards pullets, that study prompted me to put the idea to the test. Given that I have a full egg basket, and the pointy eggs taste just the same as the round ones, I've been eating the pointy ones when it comes time to hatch.
It is fine and you understand that it is not statistically reliable. For example, you would not sell round egg to someone and guarantee that they were going to hatch pullets.
What works is that some hens will lay more pullets than cockerels--figuring that out is better--until they start laying more of the other gender.
Studies to find stuff like this out only works on a large scale and over time. Next year you could get the exact opposite from the pointy eggs. Guaranteed, you are eating pointy eggs that would hatch out as pullets for you.
The closer to a 100% hatch rate, the closer to 50\50 you will get. Egg shape also depends on breed. My Pita Pintas all lay round eggs while my Penedesenca lay almost all pointy eggs.
Anyway, have fun! And do not be surprised at getting an all cockerel hatch in the future.