Scientists were puzzled by what happens in the brains of food haters
Figuring out why some people just despise cheese can reveal more than the picky eating habits of just a few people. The lead author of the French study, Dr. Jean-Pierre Royet, says, "The food aversion phenomenon exists in all animal species, from bacteria to human." Basically, every species has picky eaters, for good reason: "When a food causes illness we learn to avoid this food, and this is an indispensable condition for the survival of an individual."
Food aversion has been studied fairly extensively, and researchers can pretty reliably produce it in, say, rats: They just give the rats a food that makes them sick and watch what happens when the rats encounter the food again later. But as Dr. Royet points out, "From an ethical point of view it is not possible to artificially induce a food aversion in man."