My male dog will mount a female in heat. He doesn't give much thought, he just does it. There is no law in our country against a male dog mounting a female dog, they are not responsible for what they do. But there is a law against a man mounting a woman against her will. Unlike the male dog he knows what he is doing and is held responsible.
We are "designed" to know better. We are "designed" to be responsible for our actions. Our own laws recognize this.