Many people who had the gene found it to be an affliction, but some really liked having it. Will was one of those people, and as he prepared to go to a big party at his college, he felt intensely excited.
Admittedly, he hadn't always felt that way- the first time it had happened, when he'd looked up at the full moon from his bedroom one evening and felt his chest growing and his cock shrink away, she'd panicked, even moreso when she looked it up online and found nothing. Soon after, she discovered everyone acted like she'd always been a girl called Wilma, and she'd been even more scared. But then the next day, she'd desparately needed to go to the bathroom at school, and once there her breasts receded, her pussy sealed up and her penis grew back, and everyone remembered Will again.
He never talked about it to anyone, but soon realized how it worked, and quickly grew to love being able to swap sexes. Sometimes she'd masturbate just to make herself stay Wilma longer, since she found being a girl so fun. He enjoyed seeing how his body was developing as Will and how her body was developing as Wilma in parallel, and occasionally even sneaking glances at more masculine or feminine clothing the other self would love to have.
With all of that, it isn't hard to understand Will's excitement at the fact tonight would be the first big party at his college which was held on the night of a full moon- in fact, it was the first full moon in a couple of months. Checking the time and seeing the moon would be coming out in a few minutes, Will locked his door and stripped naked, eager to watch himself change in his dorm room mirror.
The round, bright light emerged from clouds in the dark sky, and Will smiled as he spotted it out of the corner of his eye. A pleasant tingling ran through him as his hormonal balance rapidly changed, and the young man he saw in the mirror started to change into a young woman. It was kinda like a magical girl transformation, he thought, giggling in a higher-pitched tone.
His skin was the first thing to change, rippling all over as it softened and most of the hair across it vanished. His jawline softened and his lips turned subtly puffier, and his muscles twitched and became more lithe and slim, as his hands and feet slightly shrank too. He watched his proportions change, as his shoulders narrowed and his hips flared out.
Now came his favourite part- no matter how many times he'd changed over the years, or which way, the feeling of changes in the genitalia always felt intensely pleasurable. They were totalizing, cleansing, the transmuted hormones imprinting on the malleable body and asserting the new form. Before his eyes, Will's nipples perked up, enlarged and widened as mammaries formed, so thick and puffy. He breathed heavily as warm, soft flesh sprouted around them, and smiled. Her girls were coming back in. He loved this muddled sense of gender during the change too- she was at once a boy and a girl, his desires and her desires clashing and putting him in a fuzz of flexible arousing fantasies.
But soon, her femininity overcame his manhood. His balls moved up inside her as his scrotum was sucked up closer to her body, and as his penis receded, a vaginal void formed inside her, her fantasies rapidly turning less virile and more nubile. It wasn't long before the penis was losing definition and the scrotum was having pussy lips forged from it, and thanks to the hormones, it felt amazing, like her body was correcting itself (though transforming into a man, of course, felt like HIS body was correcting itself. It was hard to put into words how right it always felt in the moment).
As his penis finished forming her clit, Wilma felt the intense feeling of the changes finally fade, and looked at her pretty body in the mirror, not a sign she had ever been a man. She pulled out a cute strapless dress from her wardrobe, stepped into it and did it up, posing contentedly in the mirror. As a boy or a girl, she loved how these looked on girls, she thought giggling. Hopefully any boys she thought looked hot would agree.