As it turned out, the type of swaps that would be happening would be gender swaps.
Anyone who swapped would retain their memories of everything as it was before the swaps began, but reality would change to accommodate the changes in gender. For example, if Jon swapped with his sister, then Jon would become the daughter of his mother. He would remember himself as a boy, but anyone who hadn't swapped would think that he was supposed to be a girl.
