Men don't like twins.
We outright hate children, but an orgasm inside a vagina makes up for that in part.
It's the math.
Two children from one orgasm, means that the existence each of those bastards is only half as justified as they think it is. The gap in perceived value is not only going to be reflected in shitty Christmas presents, but year round across the board cuts with stapling generic brand breakfast serials, boot leg sneakers and a massive deficiency in hugs and name brand hair products.
Tripplets, and worse are just asking to be wound up.