the awful truth...

The stone had been given a hard task by Jon, one which went far beyond it's usual area of extent liitations, one which it could satisfy only be altering humanity throughout time and over the whole globe--satisfying this request would make the stone useless for a decade or more, borrowing from the power it might have had into the future to fulfill the terrible wish Jon just made.
As Jon awoke, horror filled him as he realized how the wish had been satisfied.
Two children per female was far below replacement rates throughout history, and humanity can't have become extinct and Jon's wish be satisfied.
If the usual result of a roughly half male, half female fraction of births was maintained. And sign language was far too inefficient for a technological society to have developed, yet the stone felt no need to devolve society to a few hundred thousand people in crude skin clothing. Births were equally divided between males and females, but every male began to become female between the years 10 and 12, and remained females with faceboobs until they had delivered and nursed to weaning two children, and then they gradually became male again within two to three years of the end of lactation
Jon awoke to Superman sheets, and size 8 Spiderman undewear, with a child's white t-shirt on.
Bounding from his bed to a mirror, he saw himself, ten years old. Something felt slightly off, maybe enlarged even, about the tip of his tongue. Quickly pulling the T-shirt over his head, he wondered if his nipples didn't look a little bit darker pink and larger than they should. Maybe a bit tented out from the rest of his skin...