You're in luck - India and China have conducted a very large experiment on this already, though not a very ethical one. Unfortunately, it seems parents are not rational agents, and sexist societies will continue to choose male children even when women are scarce, with social turmoil as a consequence.
If you really want to fix humanity, I'd advise getting rid of men. Labs can make sperm from stem cells, so there's really no need for us anymore.
If you really want to fix humanity, I'd advise getting rid of men. Labs can make sperm from stem cells, so there's really no need for us anymore.