Conditioning is a factor, but most of my aversions date back to my earliest memories. I hated the taste of milk, cream and milk products from the get-go. I also disliked gravy, sauces and creamy puddings (and salad dressings) as "slimy." None of those reactions were the result of cultural conditioning. Reluctance to eat a nice fat grub might be cultural although if someone I knew cooked them for me I'd probably give it a try. Even as a very young child I loved beef including the fat, so I can say I was born primal. :))

Well, I'm sure some of it is innate. humans do have an innate aversion to bitter flavours and an innate preference for sweet, salty, and fat because that would have conferred a survival benefit (in eating lots of calorically dense foods which is what sweet and fat represents in nature, or in eating salt which is essential, or in avoiding bitter flavours which can signify the presence of toxins) but beyond that, I think that a lot of food preferences are just cultural/personal preference.

Also a lot of people have aversions to strong/potentially offensive flavours and textures: Think game meat, blue cheese, raw tomatoes, cilantro, etc. Stuff like plain bread is bland and hard to be outright disgusted by. Chewing a big hunk of solid meat fat on the other hand, is kind of gross.

Beyond the obvious that people tend to like what they grew up eating, if your mom could only cook something one way, and that way was disgusting, it's not a huge surprise if you have an aversion to it. I'm thinking of the typical overcooked liver, overcooked meat, and boiled-to-death green vegetables that it seems lots of people in western countries are subjected to as kids. No wonder they then can't stand those foods even as adults.

I'm not really sure of the premise of your post though. Lots of people don't really enjoy bread at all, but they love a fatty steak, so you could just as easily turn it around. Unless you've happened to survey most of the developed world :)