About a year ago, a mad scientist started setting off 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.
These mutations tended to manifest in one of three ways hidden internal mutations that left the user looking human but able to do something only an animal could life hearing like a bat or healing like a lizard, flashy transformation type powers like tuning into an animal or turning part of yourself into a animal, and permeate mutations type powers like having wings, or lizard scale-like skin all the time.
Two significant side effects would be the mutagen also caused strange hair and eye colors and sudden growth or shrinking, there was a good chance of being infused with DNA of the opposite gender; this resulted in spontaneous gender changes or developing into what is commonly called Dick-Girls and Cunt-Boys with bodies of one gender but genitals of the other. For example, in the all-girl school we are about to visit, St Grays school for developing girls, last year most of the students wore excited to have started growing breasts, but now some of them have found that they’re flat as a board again and instead have to start regally shaving their faces, and about 30% of the student body have penises where there vagina used to be.