Disgust Kicks In At Roughly The Age Of Three Or Four
Babies and young children cannot be disgusted. They don't mind their own waste products, or anyone else's for that matter. They'll eat grasshoppers and other bugs. Paul Rozin and his colleagues did an experiment in which they offered young children dog feces to eat (it was actually a combination of peanut butter and smelly cheese). They gobbled it up. As best I know, no psychologist has ever given a toddler a hamburger and described it as human flesh, but I bet that the child would cheerfully wolf it down.
Disgust kicks in at roughly the age of three or four.
-- Paul Bloom
from "How Pleasure Works: The New Science of Why We Like What We Like"
Quoted on Tue Jul 12th, 2011