On disgust-acquisition:

During World War II, American pilots in the Pacific went hungry rather than eat the toads and bugs that they had been taught were perfectly safe.

[… D]igust is manifestly irrational. People who are sickened by the thought of eating a disgusting object will say it is unsanitary or harmful. But they find a sterilized cockroach every bit as revolting as one fresh from the cupboard, and if the sterilized roach is briefly dunked into a beverage, they will refuse to drink it. People won’t drink juice that has been stored in a brand-new urine collection bottle; […]

Disgusting things come from animals. They include whole animals, parts of animals […], and body products, especially viscous substances like mucus and pus and, most of all, feces […] In contrast, plants are sometimes distasteful, but distaste is different from disgust. When people avoid plant products—say, lima beans or broccoli—it is because they taste bitter or pungent. Unlike disgusting animal products, they are not felt to be unspeakably vile and polluting. […] Inorganic and non-nutritive stuff like sand, cloth, and bark are simply avoided, without strong feelings. […]

Though disgust is universal, the list of nondisgusting animals differs from culture to culture, and that implies a learning process. As every parent knows, children younger than two put everything in their mouths, and psychoanalysts have had a field day interpreting their lack of revulsion for feces. […]

Rozin suggests that disgust is learned in the middle school-age years, perhaps when children are scolded by their parents or they see the look on their parents’ faces when they approach a disgusting object. But I find that unlikely. First, all the subjects older than toddlers behaved virtually the same as the adults did. For example, four-year-olds wouldn’t eat imitation feces or drink juice with a grasshopper in it; […] Second, children above the age of two are notoriously finicky, and their parents struggle to get them to eat new substances, not to avoid old ones. (The anthropologist Elizabeth Cashdan has documented that children’s willingness to try new foods plummets after the third birthday.) Third, if children had to learn what to avoid, then all animals would be palatable except for the few that are proscribed. But as Rozin himself points out, all animals are disgusting except for a few that are permitted. No child has to be taught to revile greasy grimy gopher guts or mutilated monky meat.

Cashdan has a better idea. The first two years, she proposes, are a sensitive period for learning about food. During those years mothers control children’s food intake and children eat whatever they are permitted. Then their tastes spontaneously shrink, and they stomach only the food they were given during the sensitive period. Those distastes can last to adulthood, though adults occasionally overcome them from a variety of motives: to dine with others, to appear macho or sophisticated, to seek thrills, or to avert starvation when familiar fare is scarce.