Well I made this thread so I've decided to add my thoughts on it all. I believe fetishes come from one of two things: Psychological trauma which leads people to a fetish. And people who have the fetish out of sheer want to be different.
For example people who have 'Daddy' fetishes where probably abused by a father figure sexually and the kink makes sense for some reason in their fucked up brain because they're first experiences with anything sexual was their dads. The other half of them you see are fucked up edge lords who think it's the In thing to be want to be fucked by daddy.
Similar examples of abuse leading to fetishes could be scat or water sports where as a child you may have been neglected or unclean or had to have eaten these things to survive and machochism almost always comes from physical abuse from a young age.
Just my thoughts though.
I'd honestly say most fetishes stem from people looking up to "iconic" moments in their childhood and are a lot more prevalent since the rise of cartoons. A good example is that weird blueberry inflation shit which, to my knowledge, completely stemmed from that one scene from Charlie And The Chocolate Factory.
If something, say a cartoon show from when you were young, had a lot of a certain subject (ESPECIALLY if one of the creators actually does have the fetish, which is something fairly common in the industry from what I've heard) and you continue to watch it into puberty, there is probably a very high chance that your first sexual experience will involve thinking about that sorta thing.
This would also explain why a lot of fetishes are dangerous/unrealistic; moments of danger or things that are super-absurd in real life will stick in a kid's mind, therefore if they think of Attack On Titan while they had a massive erection, they might get a vore fetish by accident.
There's also taboo aspects of certain subjects that can result in fetishes -- say you are a dumb kid who laughs at fart jokes a lot when they are young, then as they mature they stop finding them so funny, yet there is still this nagging feeling at the back of their mind that thinks it's super funny but it's
really not funny to everyone else; in fact, it's rather disgusting. Say they are also going through puberty -- it could result in eproctophilia out of the sheer tabooness of the subject combined with flaring hormones and a tiny sprinkle of :autism: .
I dunno tho, I'm just a guy on a Chris-Chan forum; enough playing armchair Freud.