>>1143494050/50 is most stable positon for the sex ratio.
Imagine a world where there were 20% men and 80% females. If you had a mutation that increased the chances of a man being born the amount of grandchildren you would likely have would be increased. This is because in a species where there were more woman than men these new more numerous men would have a big advantage in reproduction (since most men would reproduce anyways). Imagine the reverse where 20% were females and 80% males. Now a female increasing mutation would be highly benefitial instead since all females would likely procreate while only very few men.
This naturally pushes the ratio towards 50/50 in most sexually reproducing species.
