Jon announced "The explanation is... nothing! I look exactly like you because it's just a coincidence. So I still have my room and my family. The only thing that's different is that everyone remembers me and you growing up and looking exactly alike."
"And that you're a girl," said Karyn.
"Right. And that too. My name is Jan until I change back. Do you want to have this power too?"
"Do I want to be able to change myself, with a custom-made reality change that explains why it was always that way? Hmm..."
"Well," said Jan, "think about it for a while. But I don't see why not. It's a lot safer than wishes because you can reverse it. And you don't have to use it if you don't want to."
"Maybe tomorrow," said Karyn. How about we spend a day with you like that and see what your new life is?"
"I told you," said Jan. "I'm a girl who looks like you, by pure coincidence."
"But there aren't any details in that. What does Jan like to do, who are her friends, what do people think of her? We really don't know anything about what the new you is supposed to be like."
"Hmm, true. But I'm not sure about spending a day."
"Come on, it'll be fun. Besides, it was your idea to turn into me."
"Okay, okay," said Jan. She looked around her room. "I guess I should start by seeing what's different about the room. Let's see..." She picked up a diary, which she'd never had before, and opened it.