Let’s take a step back and explain the whole Mutant thing. About a year ago, a mad scientist started setting of DNA bombs in every city in the world. No one knows how he did it, but it was a massive event, now we live in a world where most people have animal based superpowers. A little over 80% of people and animals on the planet had there DNA fused with another.
The closest analog might be mutant abilities in the Marvel Comics, including both flashy transformation type powers like Jakes and permeate mutations type powers like having wings, or lizard-like skin all the time. A significant side effect would be there was a good chance of being infused with DNA of the opposite gender; this resulted in spontaneous gender change of developing into what is commonly called Dick-Girls and Cunt-Boys. Jake goes to an all-boys school, but now a days, most students are growing breasts and about 30% have pussies where there dicks used to be.
Other than that, the mutagen also caused strange hair and eye color and sudden growth and shrinking.
Jake is in a class of twenty, used-to-be, boys. He wasn’t the last one to figure out what his powers wore, but wasn’t the first ether.