Psychopathic Brains

A team of neuroscientists has announced the discovery of a significant difference between the brains of convicted criminals diagnosed as psychopaths and those of the rest of us. The discovery concerns the uncinate fasciculus, a channel that connects the amigdale, a part of the brain mainly concerned with emotions, to the orbital frontal cortex, which plays a key part in rational decision making. It seems that the uncinate fasciculus (honestly, how many of you have heard of the uncinate fasciculus before this?) in psychopaths is degraded. Which is quite interesting.

But what about this comment from the study's lead scientist:

If replicated by larger studies the significance of these findings cannot be underestimated. The suggestion of a clear structural deficit in the brains of psychopaths has profound implications for clinicians, research scientists and the criminal justice system.

I wonder. What does knowing that psychopaths have damaged brains have to do with how we act toward them, or how we treat them in court?

So far as I can tell, we are what our brains do. It stands to reason, therefore, that most differences between people reflect some sort of difference in our brains. At some level, I imagine, the brains of nice people are different from those of mean people, those of smart people from those of stupid people, those of the musically talented from those with tin ears. I'm not saying that these differences are simple or even consistent, but what, other than differences in our brains, could cause differences between how people think and act?

So how is saying that people's brains are not the same different from saying that people are not the same? How is saying that someone has a psychopathic brain different from saying that someone is a psychopath?