When I was a young teenager one of our neighbours worked for a "sporting goods" company. When I visited his son we pored over their catalogue which included air rifles. I couldn't afford a rifle but I did scrape the money together to buy a pistol. It was solid, heavy, like a real gun. It felt manly to hold it and point it at things.
We went out into the fields behind where we lived to kill something. I heard a skylark above us, pointed my gun at it, and against all the odds hit it! It fell to the ground and we ran over to see. It was still alive. I had to "finish it off" with another pellet. I have never recovered. It was the last thing I knowingly killed. I still can't hear a skylark without pangs of guilt and sorrow.
When my sister's son was little she made the mistake of mentioning to my dad that she was troubled with whether to allow him to have a toy gun or not. His response was to say that if we don't get our young men used to guns who is going to fight our wars for us. Talk about chicken and egg!
This desire to kill things isn't innate. It is conditioned. It is part of the bollocks mythology about what "real men" do. We should stop it. And soon!