It might be habit that developed due to constant touch with patients with diverse body problems. Actually, the feeling to ease a patient from pain developed to his system both mentally and physically.
Biologically, crimes are never passed but that sense of humor is genetically transferred from one offspring to another. As result an individual may cope varied habit that might be offensive to society/environmental norms.
Psychological theories believe crimes may be mentally triggered through exposure on given grounds for given period satisfy a habit normality. So the doctor was trigured emotionally leading to sense of mercy to given patients.
sociological,crimes occur due to the surrounding peers or subjects. The nurse was exposed to highly intensive needy patients for long so he felt the urge to relief their pain which they `might` have accepted.
Content will be erased after question is completed.