I read some article a while ago about picky eaters and how it is almost a phobia of sorts for some of them.
I think it all has to do with your early experiences with and introductions to food as an infant/toddler, and how your parents approach food and eating. When I was young, my mom was usually at home making something from scratch, and she'd always get us to help. It was a lot of fun. When she went back to work, I was about 12, and I was told that from then on it was my job to have dinner ready for everyone when they got home. I loved it, and my parents still rave about the meals I used to have ready for them. Now my mother learns from me how to cook, I taught her how to make real BBQ last year, how to brine and properly roast chicken/turkey, and my dad just laps it all up!
There is a commercial running in Canada lately with a guy in a kitchen saying, "it is your turn to cook, but everyone wants something different. Plus, who wants to be trapped in this CAGE of a kitchen? You need to finger cook! That's right, get online, go our restaurant's website and click on the items your family wants with your finger and we'll deliver it right to your door." It just makes me sick.
I have one friend who only eats plain hotdogs, plain baked pizza subs from this one restaurant in town (just pepperoni and mozza), french fries, coke, and KFC. THAT'S IT. And he dumps salt on everything. He tells me that fruit and vegetables make him sick.
I worked with another woman who only drank coffee and coke. She told me that water "tastes icky."