Mental Sex Change

"Zoe, what's wrong?" Jon asked. She looked at him and said "What's *wrong*? Jon, look at me. I'm a fucking girl!" She paused, as a confused look appeared on her face. "Did you just call me Zoe?" "That's your name," Jon said. "No, it's not. My name is Zane. It's *always* been Zane." Jon realized what was happening. His wish had caused his sister to think that she was supposed to be a boy, even though she wasn't. How was he supposed to explain to her that it was all in her head ... without mentioning the wishing stone, which he still wanted to keep a secret?