If this is a lifelong fascination, an obsession, but not a desire nor something that you wanto participate in, why do you seem to torture your own self by calling yourself sick & unnatural?
I don't understand this. Is this bec society has taught you not to like this "taboo?"
It seems like you're beating yourself up over a fetish that's kind of mainstream & I don't think you need to. Try some acceptance for your true Self.

Why do you wanto "pinpoint why you have it?" Will that do anything? Can you just accept this as part of who you are & welcome it into your Selfhood. Please don't ban it or send it away.
Imho everyone has fetishes. Some even let them off their leash.