After doing my research, I found out that my own problems were pretty mild compared to what some people experience and that for the more extreme cases it never gets better. Imagine, if you will, knowing that you will gag if you try new foods and going to a party or dinner at someone's home. You don't want to offend your hosts or make them feel like their cooking is not appreciated, yet most people don't understand this problem and will try to cajole you into trying new foods. You know you will gag or even vomit if you do--and they don't realize this. Some will even laugh at your concerns. This is a problem that really isn't talked about or explored on talk shows. So you avoid dinners, trips to restaurants, barbecues, and all of the many food-oriented gatherings as much as you can. What kind of social life would you have? How often do we do social things that don't involve food?
The only good advice I found for kids with this problem was that if kids are exposed to the presence of various foods regularly, eventually the "newness" factor would be lessened and they might try them. It's also apparent that people with this problem do better with simple, bland foods rather than spiced or complex foods. (I nearly starved when I joined the Hare Krsna temple because all of the foods had multiple vegetables in sauces and I couldn't even tell what was in them. But after a couple of months I finally got used to the smell and appearance of some and was sufficiently hungry to try them--and now I love [most] Indian food.) Texture is often a factor--some like only raw or only cooked vegetables, or like them cooked one way and not another (crisp vs. mashed and so on).
I also learned that this problem can run in families. I have a grandson who is a picky eater and my children each had certain things they never learned to like. My daughter was also phobic about eating in public and hated going to restaurants.
There's not even a standard term for this problem. Two I saw that were gaining some popularity were Selective Eating Disorder and Food Neophobia (fear of trying new foods).
Here are some sites I found:
Psychology Today article