The lesson is surprisingly informative

“So class, can anybody tell me some things they know about femboys?”

Casey could see several hands raise, though he couldn’t see much else. He decided to settle for watching Miss Jackson who was standing next to him as she called on the class.”

“They’re categorized as men.”

“They don’t have pussies even though they look like girls.”

“High libido?”

“Tiny cocks.”

That last comment stung a bit, especially since Casey heard a couple snickers.

“These are all good observations, but let’s make sure we’re respectful. All body types are beautiful and should be respected, even if they have small penises.”

Miss Jackson patted his inner thigh, sending shivers up his spine, especially with the slight air currents that blew over his cock. He wasn’t sure if Miss Jackson’s statement made him feel much better, especially since he could feel a bit of precum coating the head of his cock underneath his foreskin.

“Femboys may look like girls but you’re right, they’re classified as men because they lack female reproductive parts. Simply having a cock or looking like a girl isn’t enough to classify someone as male or female.”

Miss Jackson gently lifted your balls to show how you didn’t have a pussy underneath.

You see the screen flash to a set of tables showing some punnet squares. There were a couple groans from the class.

“Now, I know this isn’t your biology class, but because human biology is important for your health, we have to cover some basics.”

“Just like other traits can predict what kind of offspring a couple will have. A lot of other species have a very different sex determination system.”

Casey rotated his head to get a better look at the chart. He was unexpectedly intrigued and realized his simple rule change had far reaching implications that changed human genetics. He figured he could get past his embarrassment if he just focused on the admittedly very interesting lesson.

“Human sex is determined through an incomplete dominance system. If a YY man and an XX woman have children, their offspring will all be XY because each parent gives one Y and one X respectively. If an XY individual has children with a YY man, then half of the children will be XY and the other half will be YY. If we pair XY with XX, then half their children will be XY and the other half will be XX. Finally, if we have XY and XY together, their children will be 1/4th XX, 1/4th YY, and 1/2XY. This is quite different from other mammals which usually have two sexes, XY and XX, correlating with male and female. Scientists haven’t figured out why humans are so different. Any questions?”

Casey had a couple of his own but other students raised their hand first.

“So are futanari and femboys both XY? How are they different?”

Miss Jackson looked very pleased.

“That’s a great question! The short answer is we don’t know. There are a lot of factors involved and scientists haven’t figured out the exact requirements that differentiate futanari from femboys. They both have the genetic code for both male and female reproductive parts, but for some reason femboys don’t develop the female parts. We know the XY population is split 50/50 futa and femboy, but we still have a long way to go before we understand everything.”