What makes a serial killer?

Answer 1

Serial Killer is a designation that depicts a person who commits multiple murders in usually the same manner and of the same type. Most serial killers concentrate on a specific appearance of their victims. An example would be the cases involving Ted Bundy where his victims were young females with long brown hair and a slim body structure. Profilers have attributed his penchant for these women as fitting the image of his mother and a female who shunned him.

Answer 2

"It was an urge. ... A strong urge, and the longer I let it go the stronger it got, to where I was taking risks to go out and kill people - risks that normally, according to my little rules of operation, I wouldn't take because they could lead to arrest."

- Edmund Kemper -

As you can see, even they couldn't explain what was wrong with them. Henry Lee Lucas blamed his upbringing; others like Jeffrey Dahmer say that they were born with a "part" of them missing. Ted Bundy claimed pornography made him do it. Herbert Mullin, Santa Cruz killer of thirteen, blamed the voices in his head that told him it was time to "sing the die song." The ruthless Carl Panzram swore that prison turned him into a monster, while Bobby Joe Long said a motorcycle accident made him hypersexual and eventually a serial lust killer. The most psychopathic, like John Wayne Gacy, turned the blame around and boasted that the victims deserved to die.

We for certain don't know if their problem was hormonal, biological, or cultural conditioning. Even them, most serial killers answer questions with an irrational logic or connotation that doesn't makes sense. Those who answer question trustingly and humble like Jeffrey Dahmer couldn't explain the reason why neither. You can read the scientific explanations the doctors give and get lost inside those.