That's a long story :) also pretty interesting.
You may get me interested in those diseases as well LOL
Mine is a good example that sexuality is quite flexible
I do not remember anything from the age of 4 or 5, if I remember I have no clue at what age that happened. But I was born in the place and time without sex or anything even remotely erotic. I never even seen any gore or anything that could resemble guro. I even had no clue how babies are made until puberty. None of the kids around mentioned anything about sex in any way we never played doctor, I suspect that my mother also only had sex twice in her life that's when she got pregnant with me and my sister I never even saw my parents kiss.
Funny enough my sexual preferences started from guro after all as I think it was some kind Japanese movie where some general was committing harakiri, and he stabbed his belly with the sword. I had no clue what he is doing at that time but for some reason that made me aroused.
When I learned to read, my first erotic stories were fairytales that involve various mutilations. I think I was unaware of how to masturbate at that time yet. but I was kinda getting aroused when reading or watching things that involve mutilations and especially consensual ones.
The most arousing story was about the witch who asked her arm and legs to be cut to resemble the mother of the child whom she was trying to abduct. (I don't know what mushrooms my ancestors were consuming to come up with that kind of folk stories for kids but probably that was fly agaric as they grow all around)
I guess we could say that I was pretty obsessed by that as much as it was possible with the ridiculously little amount of content accessible to me and being totally clueless about sex. I had fantasies of stabbing myself with something in the belly and imagined it as it would feel similar to when a woman is masturbating with dildo except that I had no clue about vaginas and dildos at that time. None of those guro things were even slightly associated with pain or suffering. because in the fairytales cutting of a hand was less of a deal than cutting of hair. Story characters were usually very indifferent or even enthusiastic to get mutilated and probably that was the reason why I got into that. Enthusiasm is infectious. It still works even today.
However, nothing of that transformed into any sexual preferences. I had no clue about anything sex-related and just learned how to achieve orgasms by trial and error trying various strange things.
One funny thing from my childhood is that I somehow managed to convince my mom to go to the "porn" movie together(it has no sex scenes just lots of nudity). Cashier in the cinema was pretty surprised a bit to see me in the adult movie. (Now I do not remember if my sister also came along or not ) When my mom saw what is going on she declared that she is not interested and left so I just finished watching that alone but I kinda had no clue what it is all about.
I finally managed to learn about sex from medical books and decided that it is super disgusting when I thought what my mom and dad did to get me born. In fact, I kept that option for quite a long time.
Eventually, I found out that my father is interested in women with big boobs and I decided to try that as well. it worked so from that time I was interested in boobs. I was able to see some very softcore porn on the satellite and later cable tv which I "stole" and used for free. but all that was happening in my later puberty.
Finally, things changed when I got internet at that time I had absolutely no interest in guro or anything that I am interested now. I started with plain nude pictures and explored everything possible until finally, I reached BDSM Fortunately I managed to hack torturegalaxy site and had full access to it until it eventually changed its server.
My interest in guro came back only later when I discovered two pictures made by Japanese artists, which was nothing like I saw before. so I started browsing Japanese sites collecting strangest things available at that time I was only interested in plain porn as breasts pussies sex toys and some BDSM. I had no interest in Guro, lolis or scat. Scat was disgusting and I never even imagined to be interested in that. I was severely homophobic and hated gays and gay porn.
But eventually, I got into *everything*. The same way as the first time. All that was necessary just to approach it with an open mind. First It was lolicon when I just decided to try it and I liked it. Then it was yaoi as even if I hated gays that did not prevent me from enjoying the story and their relationships. Famous "Boku no Pico" hentai made me bisexual and cured my homophobia LOL. Finally, it was Scat which I also liked in anime, (but not that much in real life.)
After some roleplay and just talking with people my interests expanded even more.
But by first childhood fetishes kinda faded away. LOL