The grandparent to your post here, the one referring to "author of ZeroMQ", links to an interesting article by that "author of ZeroMQ" ... and that article is a

The grandparent to your post here, the one referring to "author of ZeroMQ", links to an interesting article by that "author of ZeroMQ" ... and that article is a "layman's rejection" of the notion that you lay out, that "psychopathy, physiologically, refers to part of the brain being underdeveloped leading to these characteristics [of non-empathy, etc.] being formed as an individual progresses through life". I was playing along with that contention, seems to make sense to me, that perhaps some people just inherit traits or predispositions to lack-of-empathy. I also don't know the psychology or neuroscience, and I imagine there's still some debate -- "is it a neurological disorder, or is it an adaptation?"