RENEE MONTAGNE, host:
We begin a series today on the criminal brain, and how breakthroughs in neuroscience are changing the way some think about guilt and innocence. One pioneer is James Fallon. He's a neuroscientist at the University of California at Irvine. For the past couple of decades, Fallon has studied the brains of murderers.
Recently, Fallon made a startling discovery. NPR's Barbara Bradley Hagerty profiles the scientist with a family secret.
BARBARA HAGERTY: Jim Fallon spends a lot of time inside the heads of psychopaths. He studies the biological basis for behavior, and one of his specialties is to try to figure out how - say, a killer's brain differs from yours and mine. It's cutting-edge academic research but recently, it became intensely personal when Fallon had a conversation with his then-88-year-old mother, Jenny.
Dr. JAMES FALLON (Neuroscientist, University of California Irvine): It was four years ago, and we were at a family barbecue in the backyard - it was in the summertime. And she said, what are you doing now? Are you still doing those talks?
Ms. JENNY FALLON: And I says, Jim, why don't you find out about your father's relatives? I says, I think there were some cuckoos back there.
(Soundbite of laughter)
HAGERTY: So Fallon investigated, and it turns out that one of his direct great-grandfathers, Thomas Cornell, killed his mother in the 1600s. And that line of Cornells produced seven other alleged murderers.
Dr. FALLON: There's this whole lineage of very violent people, killers, ending with Lizzy Borden.
(Soundbite of music)
Unidentified Children: (Singing) Lizzy Borden took an ax, gave her mother 40 whacks.
HAGERTY: Fallon was a little spooked by his ancestry, so he set out to see if anyone in his family had the brain of a serial killer. He knows what to look for, since he's studied the brains of dozens of psychopaths. He calls up an image of a brain on his computer screen. It's lit up with patches of color.
Dr. FALLON: Here is a brain that's not normal. You can see where this is - this yellow here and red here, and look at it. It's almost nothing here.
HAGERTY: He's pointing to the orbital cortex. It's completely dark. That's the part of the brain that's right above the eyes, and this is the area that Fallon and other scientists believe is involved with ethical behavior, moral decision-making and controlling one's impulses.
Dr. FALLON: People with low activity are either freewheeling types or sociopaths.
HAGERTY: Fallon says that's because the orbital cortex puts a brake on another part of the brain called the amygdala, which is involved with aggression and appetites. If there's an imbalance, if the orbital cortex isn't doing its job -maybe because it was damaged or was just born that way...
Dr. FALLON: What's left? What takes over? Well, the area of the brain that drives your id-type behaviors - which is rage, violence, eating, sex, drinking.
HAGERTY: Now, nobody in his family has problems with those behaviors, but he persuaded 10 of his close relatives to submit to a brain scan. Then he examined the images, comparing them with the brains of psychopaths. His wife's scan was normal. His mother, normal. Siblings, normal. Kids, normal.
Dr. FALLON: And I took a look at my own PET scan and saw something a little disturbing that I did not talk about.
HAGERTY: What he didn't want to reveal was that his orbital cortex looks inactive.
Dr. FALLON: If you look at the PET scan, I look just like one of those killers.
HAGERTY: Fallon cautions that this is a young field. Scientists are just beginning to understand this area of the brain. Still, he says, the evidence is accumulating that some people's brains predispose them toward violence, and that psychopathic tendencies may be passed down from one generation to another.
Which brings us to the next part of his family experiment. Along with brain scans, Fallon also tested each family member's DNA for genes that are associated with violence and impulsivity. He looked at 12 genes and zeroed in on something called the MAOA gene. It's also known as the warrior gene because it regulates serotonin in the brain.
Serotonin affects your mood, and many scientists believe that if you have a certain version of the warrior gene, your brain won't respond to the calming effects of serotonin.
Dr. FALLON: So this is the MAO gene. And we can see here my daughter, son, daughter, daughter, brother, brother, wife, brother.
HAGERTY: Everyone in his family has the low-aggression variant, except...
Dr. FALLON: I'm like 100 percent here. I have the pattern, a risky pattern. In a sense, I'm a born killer.
HAGERTY: Fallon laughs as he says this. He doesn't believe his fate, or anyone else's, is entirely determined by genes. They merely tip you in one direction or another. And yet...
Dr. FALLON: When I put the two and two together, it was, frankly, a little disturbing. You know, you start to look at yourself and you say, I may be a sociopath. I don't think I am, but this looks exactly like psychopaths, sociopaths that I've seen before.
Ms. DIANE FALLON: I wasn't too concerned. I really wasn't. I mean, I've known him since I was 12.
HAGERTY: That's Jim Fallon's wife, Diane. She probably doesn't need to worry, according to scientists who study this area. They believe that brain patterns and genetic makeup are not enough to make anyone a psychopath. You need a third ingredient: childhood abuse.
Ms. D. FALLON: And fortunately, he wasn't abused as a young person, so I've lived to be, you know, a ripe old age so far.
(Soundbite of laughter)
HAGERTY: Jim Fallon says he had a great childhood. And, he says, this journey through his brain has changed the way he thinks about nature and nurture. He used to believe that genes and brain function determine everything about us. But now, he says, he thinks his childhood may have made all the difference.
Dr. FALLON: We'll never know. But had I been abused, I think we wouldn't be sitting here today.
HAGERTY: As to the psychopaths he studies, he feels some compassion for these people who got, as he put it, a bad roll of the dice.
Dr. FALLON: It's an unlucky day when all of these three things come together in a bad way. And I think one has to empathize with what happened to them.
HAGERTY: But what about people who rape and murder? Should we feel empathy for them? Should they be allowed to argue in court that their brains made them do it? Tomorrow, we look at the brain of a psychopath and how scientific discoveries are changing our notions of morality, crime and punishment.
Barbara Bradley Hagerty, NPR News.
MONTAGNE: Want to compare the brain images of Jim Fallon and his son? Go to npr.org.