She said it was genetic

"The tests all indicate that your ... son .. had turned into a real girl, even on a genetic level." The doctor explained and looked over to you.

"What? How is that possible?" Your mother asked hearing about it for the first time.

"It's a very rare genetic disorder. Somewhere around puberty it causes the body to transform into the ideal form of a woman in the mind of the patient. And with the bodily changes the mind begins to change too, resulting in a split personality quite often."

"And what can be done to cure it?" Your mother asked concerned that she may have lost her son for good.

"From what we know ... nothing." The doctor smashed your mother's hopes. "Your ... son ... has turned into a full woman, in body and mind. All there is to wait for the change to finish and her personality to stabilize."

"See? I told you that everything was alright with me." You replied annoyed. It was Lindsey, who you had turned into during the examination. "I told you this woman is crazy claiming I'm her son. And why am I wearing this lame clothes?" You had not paid any attention to the doctors explanation until the end, so you didn't knew that that woman, your mother, was actually right. The whole talk was way to uninteresting for you to pay attention to. "If you would excuse me, I have to get out of here and get some new clothes. These rags are a no-go." You stood up and left the office.