We humans have evolved for hundreds of millions of years, and underneath our big, smart human brains we still have a reptilian brain. If someone insults you or bumps into you without apologizing, the reptilian brain says "let's kill this motherfucker!" When you got more food in front of you than you need, the reptilian brain says "Eat it all!". And when you see an attractive person, the repitilian brain says "It's fuck time!" But you are no more likely to cheat on your boyfriend with the person on the bus that you think is hot then you are to murder the person on the bus who has infringed on your personal space, because you have a primate brain that lets you control yourself and make decisions.
We all have a reptilian brain. Freud called it the "id." The id is pure indulgence without a shred of conscience, it doesn't second guess itself or feel bad because the id concerns itself with your survival. Eat, mate, and kill your enemies. That's its job. But you also have a superego, the part of your brain that suppresses impulsive desires, and the ego which balances your id and superego. Don't concern yourself with fleeting thoughts and desires, we all have them. Some people with OCD even suffer intrusive thoughts about things like killing their families, but they would never actually do it, they're no more dangerous than anyone else cause these are just thoughts.
You can't control what you think of, you can control what you do though, and it sounds like you're having no problem with that part, so you're good. It's totally normal.