AnScpFan

I just realized while replying to this that it was a typo check the description of the story

You see it said 90% were born with the organ OR developed it by the age of 10 I get how it can be confusing though :)

Great story. It has an interesting premise and the characters are already lovable a few chapters in also the undead seem to have a more goofy aura while the other characters seem to be more serious making it all the better.