Psychopathy is a behavioural disorder. They renamed it sociopathy in the seventies (or maybe earlier) because it was social ie not biological. In the end, the name change just seemed to cause confusion.
I know there are now some claims psychopathy is biological but the nature/nurture pendulum swings back and forth. Right now, in the age of the genome, we are in a period where many people want to believe everything is biological/chemical/wiring.
There is, however, a very vigorous debate about this, especially outside North America, where they don't buy into this "it's all chemical" stuff.
Of course it's a behavioural disorder. But behaviour is both biological and moral/ethical in nature. I don't know of any serious scholars in the field who believe that it's "all wiring" (or genetic, or what-have-you).
What the evidence is tending to show, however, is that there is a neurological basis for psychopathy, but not that it is determinative of same. In other words, having the particular abnormality of the amygdala or angular gyrus doesn't mean a person will become a psychopath, but it does make that person at greater risk, just as having certain characteristics of the occipitotemporal area of the brain predisposes a person to dyslexia but does not mean that the individual will inevitably develop it.
Environment/epigenetic factors also play a major role in whether a biological characteristic (whether inherited or a genetic "sport") will express itself in a particular manner. There is nothing fatalistic here. No one absolves the individuals concerned of their responsibility for who they are and what they choose to become.
The acknowledged expert on psychopathy is Canada's own Dr' Robert Hare, who has written an excellent and thoroughly readable book,
Without Conscience: The Disturbing World of the Psychopaths Among Us which you can probably find at your local public library (HPL has it) or get at low cost from Amazon. He comes down on both sides of the fence, heredity AND environment, as many scientists are doing in a number of fields (heart disease, mental illness, etc. etc.) The newer field of epigenetics also sheds a lot of light on these matters (see :
The Dependent Gene:The Fallacy of Nature vs. Nurture by David S. Moore).
Neuroscientists are studying the abnormalities of the brains observed in both autopsies and fMRIs of psychopathic subjects; they lack of course possible comparison to brains of "pre-psychopaths" that is, children who might become psychopaths. Hare is concerned with developing ways to possibly identify them in order to put preventive therapies in place. Adrian Raine, currently at the University of Pennsylvania, is developing a system for identifying people at risk of psychopathy early enough to intervene. Some interesting correlations (remember that correlation does not equal causation) between physiological traits demonstrated in young children and later psychopathic or criminal individuals are under-responsiveness of the autonomic nervous system and low skin conductivity.
Hare, Raine and others have written a number of scholarly articles, which I am resisting the temptation to cite here, but you (ABro) may find this youtube video to be of interest:
[video=youtube;6PpKdwWHDMA]https://www.youtube.com/watch?v=6PpKdwWHDMA[/video]
.. but read Hare first, if you haven't already. You will
definitely find it a compelling read.
The "it's all biology" and the "it's all environment" folks are both out to lunch. Humans are complex beings, and our biology and our minds and spirits all interact with our environment and can't be discretely compartmentalized.
I could go on but promise not to. Cognitive science is my professional area of expertise and I'm well read in it. It's fascinating stuff with many real-life applications.