After reading a book on the brain, I find myself thinking that no one is really responsible for their actions. I don't mean this so much in the "no free will, everything is determined already" sense, which seems a little bit dubious, but rather in a broader sense. If "we" are really just the product of our genetics and our environments, how are we to be held responsible for what we do? If someone commits a crime because his/her brain is underdeveloped, or badly developed (think: underdeveloped prefrontal cortex -> impulsive decisions), how is he/she to be held personally responsible? Our legal system seems to make the implicit assumption that everyone is in control of how they act; that everyone is on the same playing field. But we really aren't. Looking at that, it doesn't look too Reddit-y. It's a touch different than the standard brand of liberalism you get from the most upvoted comment in r/politics, at least.
A person is identically equal to whatever was created by the circumstances of the universe. It's hard to come up with a good way to say this. I just don't see any difference between holding someone "personally" responsible for their actions and holding the product of genetics and environment responsible. I think what you're more opposed to is a punitive justice system rather than a corrective one. Give people an environment that is likely to change them for the better for society rather than pointlessly punishing them. Punishment is a futile exercise in revenge unless it is also effectively corrective discipline. I think that is what our justice system (in the US) is supposed to do, but it utterly fails at it.
I think you're right. There is some merit to putting people who might pose a danger to society behind bars, but this only addresses half of the issue. I'd like to see a justice system that recognizes ways to help those people develop into functional human beings. From what little I know, Scandinavian countries already take this approach, to some extent; is it working, I wonder?