I tend to think that actual psychopaths would be more inclined towards types that use extroverted thinking and introverted feeling though, probably TJ but maybe FP, not FJ or TP. I've heard that psychopaths are often very good at feigning emotions and at understanding emotions in others, but are unable to empathize. That sounds like much stronger Fi than Fe to me. They would not care how they get along with others (Fe), but would strongly feel that they want things (Fi) and focus on efficient ways of getting them (Te).
Please don't start a discussion about which one - Fi or Ti - is more "selfish" (which is a word of any interpretation anyway). From my Fi/Te balcony the Ti/Fe is selfish in its own very different way, and apparently it's hard to see one's own way, so I'm pretty sure I don't realize my own well enough too.
In the end - speculations - are useless. Until there is a record of multiple decades/generations, with strong correlation proven, any such claims better not be discussed. ISTP is not the most common male type, by the way; ISTJ is.
Back on topic, I think there's too much assumption already in the usual accusative language. What exactly is "fault", what does it imply? What is its real meaning? It means a group of people gather to punish someone for doing something, that's what the word practically means. Is that acceptable, and is it useful? What is learned from that?
The studies that find correlation with bed-wetting for example, are based on reports. It would mean that there is stronger correlation with criminal behavior in people whose parents treated bed-wetting as something abnormal and probably even punished them for it, so it became a big deal, and was reported specifically. Why freak out so much of things that are so biologically normal? As if our bodies have had time to evolve and match with modern bed sleeping. And then, of course, if the little kid is traumatized by the shame and fear which some parents produce out of such innocent act as bed-wetting, this could have potential in some cases to combine with other factors and play its part in developing antisocial behavior.
I agree with studying people who commit murder, most importantly what influenced them, but I disagree with treating them as in any way inferior, punishable, or sub-class of humans. If anything, this attitude motivates society to treat each other this way daily, with endless suspicion and threats, which is not the way to resolve the problem, and rather re-iterates it.
They do have a moral code. It is very simple. What they want is good and what gets in the way of it is bad. You are not a being. You are a thing to them.
And I thought this has always been seen as honorable in the hollywood-induced culture... the irony. Also, they'd make the "perfect" CEOs, woot.