I have been the same way my WHOLE life!!
I would eat pizza, but without the sause.
I would eat noodles plain..no butter, no sauce, no seasonings.
I would eat peanut butter sandwiches but NO jelly.
I never and still don't eat ketup, mustard, or mayo.
I never ate salad dressings or other types of sauces.
Just in the past few years (I'm almost 28 ) I've started eating different things and have found that I like them.
Some things I don't like but they aren't awful either.
Things that I can tolorate I try to keep eating them so that I can get use to them. It seems to work and I eventually like them just fine.
I now east pizza sause and some salad dressings. I no longer eat my noodles plain.
I don't eat a whole lot of new things but I'm working on it.
It's def. a mental thing, for me at least. I have to just stop thinking about it and try it. That's easier for me to say than actually do.
I try something new maybe once every few months.
I can say in the past few years of trying new things I have gained weight which I'm not happy about but currently working on.