I’m pretty much in the category of someone who can/will eat anything. But one of my brothers will not eat fruit of any kind - ketchup and orange juice are as close as he’s willing to get to “fruit.”
There are definitely biological factors. You can look at the way kids favor carbs and protein. As they mature, they’re more likely to appreciate vegetables and other foods with bitter or sour notes. That makes sense if you’re pushing to grow quickly - a craving for celery is not going to make you big and strong by itself.
But so much is mental. I’m not an expert on the research, but I do know that the olfactory bulb of the brain is wired differently than any of our other senses. I’m sure there are experts who can clarify, but I’ve heard that responses to smells are processed more like reflexes than something like sight is. Since smell is actually 95% of taste, I think we can point to the wiring of olfactory bulb as being more important than issues like taste buds.
In any event, the wiring makes it more likely for smell to get an almost instinctive association of good or bad that bypasses conscious thought. Thus, one bad experience with fish could produce a subconscious “fish=sick for days” association that will keep you away from it even if your conscious brain can say “Yeah, but that was just once.”
There are also some associations that have to be learned, but seem to be biologically reinforced. I’m thinking of a study done with monkeys who watched video other monkeys reacting fearfully. In one set of videos, the filmed monkeys reacted fearfully to a snake; monkeys watching that learned to react fearfully toward snakes, even when they’d had no prior exposure to snakes. In another group, the monkeys saw video of other monkeys being fearful of a flower (edited in, in place of the snake). These monkeys did NOT learn to be fearful of flowers, despite no prior experience with flowers. And, having no experience with snakes, were also not fearful of snakes.
Assuming that applies to more than monkeys and snakes, it would suggest that there are certain foods we’ll rarely hate (mac and cheese, say), even if there’s lots of negative signals, and other foods that we’re predisposed to avoid (seafood, say), even if we have only a little negative input.
But there’s one that my body resists like crazy - celery. For some reason I cannot eat it; it is like trying to ingest motor oil. It doesn’t even register as food. I was sitting across the table from someone who was eating celery and the smell turned my stomach. And then there was someone else I once knew who cannot stand the smell of fish, even from across the table.
