incubus genetic defect is whenever the person that has it is an Incubus, they can't eat normal food and can only live off of male s*men after they become of age, they look like normal humans but are normally born with two different colored hair or eyes, but not always. Shoto Todoroki was born with this defect and recently found out whenever he turned 21. Normally this defect develops around 17-19 but Shoto ended up being a "Late bloomer". Whenever Shoto found out this about himself he didn't know who to go to about it, he was slowly starving to death.