Discomfort of Killing

I am working to better understand whether all (or nearly all) people experience stress or discomfort while killing animals, and whether that stress or discomfort is due to social norms or it is wired into our biology.

Many hunting and gathering peoples had elaborate rituals related to the killing of animals, and even grizzled old ranch hands show many “tough guy” coping mechanisms. Rancher children are all in tears for years about animals dying until they “toughen up“.

Do you know where I might look to better understand, or find support for, the idea that nearly all humans experience stress while killing animals?