I saw an interview with Dahmer once where the interviewer was poking around his childhood, his parent's marriage, his mother's rages. Basically asking if his volatile home caused him to become a murderer. He was like, no, there has always been something wrong with me since birth. I think he said at around 5 he knew he was fucked up. He tried to control it but he couldn't. He said (I think) he deserved to die.
I was saddened by that. That he knew he was broken. He had enough self awareness to try and stop. Too bad he didn't just off himself.