Hold the Olives

Why do we like or dislike the taste of certain foods? Is it psychological? Physical? I was at the Subway sandwich shop earlier this evening, picking up a sandwich, at the "sandwich artist" there (a former student) suggested black olives. I had to tell her that I don't like black olives (or green olives, for that matter). When I was a kid, I wouldn't eat cauliflower, but I do now. I used to not like nuts, other than peanuts, but these days I'm alright with walnuts in ice cream or cashew chicken at the Chinese restaurant, for example. I also remember not wanting to ever try mushrooms as a kid, 'cause I was afraid they'd be poisonous; later in adulthood, I ate mushrooms with just about everything. I still can't stand the taste of olives, though. I wonder why that is.