I want to install the surgy mod but I don't know how to do it. Do I have to drag everything from the mod folder into the game folder?Ghouls are from Complex Breeding mod. They evolve from humans. You can read their evolution conditions by hovering the mouse cursor over a human's race name.
Ghouls' evolution conditions are complicated - the human has to be sick and/or heavily damaged for the chance to give birth to a ghoul to happen. And they might also need eternal essence, but I'm not sure about that.
Can you clarify which mod you are talking about, and where it is?