there are some other theories, including that Y chromosome sperm swim slightly faster than X chromosome sperm or that female embryos have a slightly higher chance of miscarrying. so they’re saying that the current view is that the ratio of X and Y sperm produced is what makes the difference, not the other theories.

my dad has a X and he would frequently use it upside down from the moment it was out of his pocket, not just in one app. i know this bc it annoyed me.