Just hopping in and its good so far but I have to ask.
Did I miss... like some required lore reading? Cause certain things are making me very confused. Still going to keep reading, just wondering.
I'd say things are confusing by intent, at least for now.
But the gist of it is
some sort of epidemic killed all man and in the decades since the women managed to keep humanity going through a combination of pre-existing sperm banks, cloning, recombination in vitro and other tricks. Boys being born would stil happen in the beginning but they all died still in infancy, so doctors probably started to select for only girls to avoid the ensuing stress/trauma for mothers.
So the boy being still very much alive
and horny at his age is supposed to be an improbable miracle and incredibly sus at the same time and definitely plays a part on the reasons behind his supposed kindnapping as a baby.
Either genetic manipulation of the twins or some weird supernatural mojo at play (also hinted at in parts), if not both, is possible not to say probable.