Have you ever acted out those thoughts, Dnester? I remember your previous threads where you said no, they are just thoughts. Everyone has bad thoughts, sometimes really inappropriate, even violent thoughts. I think that is normal and, individually, we all have our own variety. The more important thing is how we manage them, or even perhaps not manage, but whether we DO anything in response to them. If not, and you have been able to keep them to yourself well into adulthood, why are thoughts a problem at all? Of course they can be a problem even internally if they cause discomfort, anxiety, or excessive self-flagellation. If that is the case, it may be worth working on why you emotionally react so strongly to mere thoughts. But thoughts alone do not make someone a bad person! It might actually make you a good person if you know your thoughts/desires would be inappropriate/harmful if acted on, and you are able to successfully self-regulate and keep them in your head. Or maybe find a sort of Sublimation-type transformation/act (look up in psychological defenses if you are not familiar with it).

The reason might simply be being born human and nothing else.