Karyn didn't change?

The front doorbell rang and Jon went out to answer it. He opened it and... it was Karyn. She looked just like she did before. "Hi," said the newly female Jon. "Hi?" said Karyn. "Jon, what's wrong? You're staring at me. You're acting so strangely it's taken me around ten seconds to tell. That's pretty bad." "You're a girl!" "Of course I'm a girl!" replied Karyn. "I've been a girl for several years now ever since I started puberty, just like you!"