Well, let's say one has been brought up in a harsh environment, with harsh not much loving parents also due to their own upbringing with all their fragmented and dissociated psyche's. A situation that is quite common even to this day...
One then becomes desensitized to their own feelings and sometimes empathy flies out the window too, given this occurs fairly early when one is impressionable, one does not even recognize the difference in himself and others if his (predominantly) or her intelligence is average.
However, in the case where one even has an above average intelligence (in the most notable cases), they might be able to recognize this trait in themselves; but, here is the crux, they more often than not exploit this facet of their personality and see it as a
strength (comparative evolutionary advantage within game theoretic bounds) given therapy is a much more arduous, alienating, and astigmatic path to take which is further compounded by the fact that such individuals are desensitized to the process of learning via emotional reasoning. Coming to terms with being the way they are is often more off putting than accepting themselves and integrating with the rest of people. Often narcissism makes the task more difficult.
The common (calculative and analytical) mindset for such a person is to view people as objects interacting with each other to maximize their own utility. Now, if one feels compelled-given a desire to have children, as I doubt even such non-empathetic people are incapable of love albeit
in a different manner, then they feel compelled to pass on what strengths they have found in themselves to their offspring and disguise their love in anger, frustration, indifference and all the other resultant emotions from a lack of being able to feel adequately or empathize.
Now, the whole thing becomes
pathological if the offspring have a predisposition to such non-empathetic traits, although sociopaths are said to be a product of nurture, and the circle closes.