I know someone who became convinced they were gluten intolerant (which is discrimination imo) because everytime they ate this one thing they got a rash and they couldn't find out if it had gluten in it or not, which of course is the rational conclusion to come to.
They also thought they were lactose intolerant, but only to pasteurized milk, so they only drank soy milk. But cheeses and ice cream were fine. Or something. I don't know.
They also hate mushrooms, which would be a felony if I was in charge. Which of course I wouldn't enforce by violence but polite suggestion.