Some people don't have a consciousness. Simply because their parents didn't tell them right from wrong. There's also the part where they listen and copy what their parents do, and also the relapse of what happens in their life that they have seen once and find so fascinating. Kids are like a mirror, they reflect what they learn. Then as they grow older, what they took for granted and not corrected on, becomes a part of them, and no matter how long you take to tell them it's wrong, it's like cutting a huge piece out of their life, which obviously is impossible. This is why rehabilitation doesn't work, because instead of correcting them, all it does is it let's them know that the same thing is gonna happen unless they find a way around it, which is much easier than completely changing who they are, this is why they can't find a job, because it's their choice to carry on re-offending rather than moving on with their lives. Once you get comfortable doing wrong, you won't feel comfortable anywhere else. This is because doing evil is more acute for humans than doing good.
