Bestiality is a hide mechanic that can be turned on and off based on your action towards the feral enemies. If, during the battle, you see the Dire Wolf art with his sheath exposed, it means it's toggled on.
If you do not feel comfortable with them, just don't build a good reputation with them and the game won't be using it.
By my experience, the first time I played I didn't even notice we could actually have sex with ferals lol. I just noticed on my second gameplay, since I am building a loving rep with all enemies.