Shocked, Karyn realized: everyone had Incan ancestry. In fact, everyone had ancestry from anywhere. No matter what race you are, human beings had intermingled so much that by the 21st century, everyone's ancestry is from everywhere on the planet. If it was just this town, the stone could make Jon into an outsider, but there really was no simple way to keep him from having Incan ancestry and have him still exist.
She needed something that wasn't so simple. Like...
Karyn picked up the stone and made her wish.
"I wish that Jon exists, because he's someone's clone, and the Incans, who never heard of cloning, wouldn't count anyone as a clone's ancestors, not even the person they were cloned from. I wish that he remembers his life before and after today's wishes and knows what changed."
Which worked. Jon, suddenly, rematerialized. But Karyn made two mistakes. First, she didn't tell the stone whether she wanted a realistic clone, who just looks like a younger version of someone else, or a sci-fi clone, who's the exact same age and has the same memories. Second, she didn't tell the stone who Jon would be a clone of....
Jon finished his sentence "...mitations" and then yelped, startled at his new memories and new body....