A recent episode of NPR's Hidden Brain called Crickets and Cannibals talked about the idea of disgust and how it's a learned instinct.  Most, if not all, traits we consider instincts are ingrained from birth.  Survival, how and what to eat, and rearing young are all generally things that will happen without learning them.  Disgust is sort of different in that young children aren't disgusted by things like poop and snot, but they learn those reactions and then internalize them as a sort of instinct. 

This is especially obvious when considering the diets of different people groups from around the world.  What we eat is essentially prescribed to us by our culture, and that's not entirely a bad thing.  But you really don't have to look that far to see cultures that eat horses or bugs -- animals that are considered immoral or repulsive to most Americans' palates.  But there's nothing inherently immoral or repulsive about eating those things.  Horses are essentially just skinny cows, and bugs are called shellfish when they live in water.  We obviously have no problem eating either of them. 

The main problem is that disgust is a particularly difficult instinct to break.  It's clear that certain "disgusting" things really aren't disgusting and are merely the instincts learned from our respective culture.  But knowing that fact doesn't change how we feel.  I ate a cricket protein bar once, and aside from it not tasting very good, it was hard to get over the idea that I was eating crushed bugs.  It really shouldn't bother me; plenty of people and animals eat bugs, and crickets are an efficient source of protein.  But it still wasn't a pleasant experience.  I wonder how long it would take, or how many repetitions would be required to break a person's learned disgust? #psychology