Not trying to be snarky, wikipedia's article on psychopathy has a good explanation on the subject. Questions of law and safety aside, I don't think we should pass judgment on anybody by calling them inhuman or evil. We're all human.

Generally I agree with the counselor’s sentiment. That seems to be true for most of us at least, and I have anecdotally heard of people who could be called sociopaths with a conscience. They may think cruel things but behave well and display empathetic behaviors whether or not they’re genuine.

I do think evidence supports a tragic level of determinism. Most everything seems like an inevitable reaction if you break it down far enough to cellular behavior and brain chemistry. The truth is probably somewhere in the middle. Between nature, nurture, and chaos, we definitely have less free will than many imagine, but the small part we may have offers just enough constraint to make creativity possible. Creativity is hard to accomplish without some limiting parameters to urge you in a certain direction. When you’ve only got a limited set of options, that’s when self expression becomes vital.

As I said on the last post I saw talking about free will today, I don’t believe we have much if any of it, strictly speaking, but it’s best to labor under the assumption that we do. People definitely can choose to better themselves, but whether or not they will could practically be biologically predestined for all I know. The notion I like regarding mental health is: thoughts are like birds. You can’t control which ones land on your head but you can decide which ones make a nest there.

Sociopaths lack working mirror neurons (empathy) and so do not see the problem with harming others.

It's a hard problem.

The truth is that non-sociopaths have lots of emotions to help them see that maintaining trust relationships and social reciprocity is in their long term rational self interest, or we'd all tend to be selfish and self-serving. These emotions are both positive (e.g., the good feeling you get when you've earned security and trust in a social group, or when you help someone in need because you know that is likely to be generally reciprocated) and negative (e.g., guilt or shame when you harm others, or a sense of abandonment if socially shunned). Imagine having to slog through every day delaying personal gratification and doing the Right Thing when all it means to you is sacrificing what you want in the moment for some nebulous, abstract benefit that you never really FEEL and which may be some distance into the future.