Would her lack of stability (manic mood swings etc) have helped accentuate these tendencies I think I can see in her boys?
Maybe the lack of home stability might have not so much accentuated the tendancies. What it might have done is not provided a good strong nurturing environment for them.
From what I've read that seems to be vital in giving people a chance to acquire an ethical values system that sticks. Empathy is a strong tool in becoming a decent person, but in the end giving the boys an environment where they had a strong habit of consideration for other people, for ethical behaviour etc would have been the best way of turning them into people who behave decently.
Also if their mother was unstable, they may have learned that manipulation was a survival strategy. Someone who's struggling with emotions/perceptions can be all too easy to manipulate, sometimes as a necessity if you're powerless. But it's a tool that's hard to put down once you know it works - especially if other peoples' unhappiness isn't something yo care about.
Might MIND be a good place to start? Most of what I've picked up was from professional MH workers myself. MIND has leaflets on personality disorders and almost certainly has recommendations for further reading.
(one thing I find is that under extreme stress, almost everyone has the capacity to act like a real bastard. The problem is that people with ASPD, that capacity is far closer to the surface. But we can all be rotten in the wrong circumstances, if pushed far enough).