No idea really. I looked at (real) gore on the net as a kid, but never sexually and pretty much always with disgust and horror. Hell, I remember coming across a link to gurochan when browsing /b/ back in 2009 and making a thread about how "how can you guys be into this sick filth" lol.

I guess I just got desensitized to violence over time, my latent sadism combined with growing misanthropy helped too. But mostly, it was just a gradual expansion of fetishes, combined with some entry level "kawaii guro" stuff that was just cute as heck that made blood and guts look beautiful. Then again, guro isn't my main fetish or anything. Just a side thing I like to indulge in every now and then.