I was just reading the Picky Eaters trope on TV Tropes last night, and I learned some interesting things. Apparently there is a name for people who can only eat certain kinds of food and everything else is like poison to them. Food neophobia ,it's called. They make other people who are picky about their food seem normal, which it pretty much is. Nearly everyone has some kind of food they hate or can only eat it a certain way.
I also read that a hatred of green vegetables is actually some genetic survival thing. Many green things have a bitter taste, and many things that have a bitter taste are poisonous. Rhubarb leaves, for example. And it tastes worse to kids because their taste buds are more sensitive. So I guess other kids were technically doing the right thing all along, while as a kid I ate -and enjoyed- green leafy salads and green beans and peas. There are three vegetables I hate and two of them aren't even green (on the inside, anyway) - turnips, squash, and cabbage. I'm also fussy about potatoes. It depends on how they're cooked. I can't handle them mashed because of the way they stick in my throat. And if turnips are mashed into them, forget it!
I think my nephew, who is autistic, has selective eating disorder. Trying to make him a meal is a bit stressful for my mother.