Indeed. I think I've heard about this guy on the radio. When it comes to the 'murdering psychopath' twist, it was identified that you not only needed the genes, they also generally had to be 'activated' by a horribly abusive childhood.
IE you have a reasonably well adjusted member of society if you raised your potential psychopath well, or a person without the genes horribly(sad as that is). It's only when the two mix that you get serial killers.
Just because you're a psychopath doesn't mean you need to be a murderer - as I like to joke: 'I'd have no problems killing you, but hiding the bodies is such a pain'.
Personally, I believe in the 'social contract'. Humans are NOT set up to 'go at it alone'.