If Thanos had, instead of randomly wiping out 50% of all living things, he had instead in each species wiped out only the dumbest 50% what would the reaction of each avenger have been?
Has to be more than that. People can have multiple children and probably would have more just because they can. It'd need to be cut to at least one third or less.
Non-zero chance that the distribution of infertility does not match the distributions of male to female. Could result in complete population collapse pretty quickly.