You’ve got to read or listen to this NPR story. It’s about neuroscientist Jim Fallon, who has made a career of studying the brains of psychopaths. A few years ago, his aged mother told him he should research his father’s family tree, because she thought there were some nuts in it. Turns out that there were a lot of very violent people in it, going way back — including, get this, Lizzie Borden!
He knew what the brain scans of psychopaths looked like. Then he examined a scan of his own brain, knowing what to look for (that is, how the psychos’ brains differed from normal brains).
He had the brain of a psycho.
It gets worse: genetic testing showed that everyone in his family had a gene that made them susceptible to the calming influence of serotonin — except him. He had the perfect brain of a psycho killer.
But he is not psycho killer. Why not? That’s the hopeful part of this story. Excerpt:

[Scientists] believe that brain patterns and genetic makeup are not enough to make anyone a psychopath. You need a third ingredient: abuse or violence in one’s childhood.
“And fortunately, he wasn’t abused as a young person,” [Fallon’s wife] Diane says, “so I’ve lived to be a ripe old age so far.”
Jim Fallon says he had a terrific childhood; he was doted on by his parents and had loving relationships with his brothers and sisters and entire extended family. Significantly, he says this journey through his brain has changed the way he thinks about nature and nurture. He once believed that genes and brain function could determine everything about us. But now he thinks his childhood may have made all the difference.
“We’ll never know, but the way these patterns are looking in general population, had I been abused, we might not be sitting here today,” he says.

Biology is not destiny.