As I said, it has been proven to be a fallacy when talking about chicken eggs. Whether or not that can be applied to game birds is unknown.Theoretically, they should be 50/50 but the reason I started this experiment is because I noticed a few years ago I was hatching a disproportionately number of male birds. Then began putting the observation of pointed eggs versus round eggs into the theory. It sounds crazy and 'theoretically' shouldn't be but that has been my observations.
I have hens that lay both types, pointed and round. And others as you said, some only lay pointed and others only round. Some of the ones that lay the blunt eggs tend to lay some of their eggs that are actually completely round! I have also noticed that those eggs are almost never fertile and if they are, the embryos will 'quit' somewhere along in the incubation process. I haven't broken it down that far as to what each of those hens eggs turn out to be, yet.
The reason I'm using Goldens and Amherst only, is because they can be sexed at hatch, whereas with the True pheasants, I would have to band or mark them somehow to 'wait' and see what sex they are...also easier to get them mixed up in the banding or marking process. With the Ruff pheasants I'll know immediately.
Basically, just doing this for my own curiosity, and see if it's just a fallacy or if there is something behind the observations.
I also suspect that like humans the game birds are probably not expected to be 50% of each sex.
"What is the ratio of boy to girl births?
While historically, there have been about 105 boys born for every 100 girls worldwide — which creates a “sex ratio at birth” of 1.05 — the share of boy babies has increased in recent decades. 2011 data from the World Bank show the global sex ratio at birth is now 1.07, or 107 boys born for every 100 girls.Sep 24, 2013"
The theory is that those populations that have a tendency for male deaths (war, etc.) will produce more males than females at birth.
The other problem is having a sufficiently large enough sample size to meet statistical expectations.
When I was raising Slate turkeys, it is statistically expected to hatch 50% Slates and 50% Self Blues when breeding self blue to slate. I had hatches that would come out 90% self blue and others that would come out 90% slates. Over the course of a full season they did meet the expected results but not necessarily during each hatch.