An actor plays the role of Lizzie Borden at Killers: A Nightmare Haunted House. Professor Fallon is related to seven supposed murderers. Among them is one of the most notorious suspected killers in US history, Lizzie Borden.

London - On just a normal day in the office, James Fallon made the most shocking discovery of his life. In October 2005, the professor of psychiatry and human behaviour at the University of California was working on his special subject — the brain scans of psychopathic murderers.

“These are some of the most dangerous people you can imagine,” he says. “They had done some heinous things over the years, things that would make you shudder.”

During 20 years of analysing brain scans, he’d noticed how cold, hardened murderers had alarmingly low activity in the frontal and temporal lobes of the brain — the areas associated with empathy and self-control. Without that self-restraint, they became crazed killers.

That day in the city of Irvine in Orange County, Professor Fallon was working on genetic tests and brain scans of Alzheimer’s patients, comparing them to the results for his family, used as a control group.

Flicking through the family scans, he came across a particularly odd one. It showed all the classic traits of a murderous psychopath.

He assumed his family scans had got mixed up with the scans of psychopathic murderers. Horrifyingly, they hadn’t. When he cross-checked the reference number, he had the shock of his life. It was a scan of his ownbrain.

The 66-year-old, happily married father of three had led an exemplary existence, with a highly successful career at the top of his field. But he couldn’t deny the evidence staring him in the face.

“I am basically a normal person, except for one thing. I’m a borderline psychopath,” he says.

That wasn’t the end of it. Professor Fallon then searched his family’s DNA for genes that are associated with violence, particularly the “warrior gene”, which controls the amount of the hormone serotonin in the brain. Serotonin has a calming effect, unless a person has the warrior gene, which prevents the hormone working its magic.

Guess what? Every member of his family had a low-violence genetic structure — except one: Professor Fallon himself.

“I’m 100 percent,” he says. “I have the risky pattern. In a sense, I’m a born killer.”

It gets even worse. It turns out that the professor’s ancestors have made a speciality of killing.

One day at a barbecue, his 88-year-old mother let slip a dark family secret.

“Jim, why don’t you find out about your father’s relatives?” she said. “There were some cuckoos back there.”

Pretty violent cuckoos, too. Professor Fallon is related to seven supposed murderers. Among them is one of the most notorious suspected killers in US history, Lizzie Borden, or “Cousin Lizzie”, as Professor Fallon jokingly calls her.

In Massachusetts in 1892, she was tried and acquitted of killing her father and stepmother. Despite her acquittal, she became the subject of one of the most popular skipping rope rhymes in America:

“Lizzie Borden took an axe

And gave her mother 40 whacks.

When she saw what she had done

She gave her father 41.”

And a direct ancestor, Thomas Cornell, was hanged in 1667 for murdering his mother.

Professor Fallon, though, has never hurt a fly, despite having an overwhelming genetic and neurological tendency towards psychopathy.

The realisation of his condition has changed his intellectual approach to the relationship between the brain and a person’s character.

Before the discovery, he thought genetics determined your future — character was down to nature, not nurture.

He has studied the brain scans of dozens of psychopathic killers and, again and again, has found the same results.

Compared to a healthy brain, the killers’ brains had much less activity in the orbital cortex and around the amygdala — the areas that prevent impulsive action and control social behaviour, inhibition, morality and ethics.

Examining his own brain scan, he saw the same killer pattern. His brain has dark patches of low activity just behind the eyes, in that crucial orbital cortex area.

“People with low activity in that area of the brain are free-wheeling types or sociopaths,” he says.

Now he believes the right sort of nurture can overcome the most evil form of nature. And the best sort of nurture comes from adoring parents.

“I was loved and that has protected me,” he says.

His parents’ love, it seems, saved him from a life of violent crime and steered him towards a highly successful career. But it couldn’t stop the vestiges of his psychopathy emerging in different ways.

“I’m obnoxiously competitive,” he says. “I won’t let my grandchildren win games and I do things that annoy other people. But while I’m aggressive, it is sublimated. I’d rather beat someone in an argument than beat them up.”

In his youth, Fallon suffered from panic attacks and an obsessive compulsive disorder, repeatedly washing his hands. He would stand up to bullies in bars, but never felt the temptation to fight them.

“While many of the males in my family are athletic and several just love to fight, I never developed a taste for pugilism,” he says. “I prefer to mentally pummel someone than use bare knuckles.”

So, how has his shock discovery changed him?

“Since finding all this out and looking into it, I’ve made an effort to try to change my behaviour,” he says.

“I’ve consciously been doing what is considered the right thing to do and thinking more about other people’s feelings.

“At the same time, I’m not doing this because I’m suddenly nice. I’m doing it because of pride, because I want to show to everyone and myself that I can pull it off.”

Professor Fallon’s discovery about himself has made him fine-tune his study of what constitutes a psychopath.

There is no rigid psychiatric diagnosis. In fact, it is defined simply as an anti-social personality disorder in which three or more of the following seven conditions feature: irresponsibility, deceit, reckless- ness, indifference to the welfare of others, a failure to plan ahead, aggression and irritability.

Professor Fallon says the depictions of psychopaths in horror films and thrillers — such as Freddy Krueger in A Nightmare On Elm Street — are grotesque exaggerations.

He also says that Patrick Bateman, the self-loving, unhinged character played by Christian Bale in the film American Psycho, is not representative of a true psychopath. “He is too violent to be realistic,” he says.

However, the professor thinks the violent Mafia mobster Tommy DeVito, played by Joe Pesci in Goodfellas, is closer to a realistic depiction of a psychopath.

“They are relatively normal-looking people who you might pass on the street and not think twice about,” he says.

“But they are deeply disturbed individuals who ultimately cannot control their innate aggressiveness and show little regret or sympathy for their violent actions.”

To produce those characteristics, it appears, it’s not enough to have the genetic or neurological psychopath brain pattern. That has to be accompanied by a family history of abuse or violence.

Fortunately for Professor Fallon, his family has enabled him to overcome his genetic and neuro-logical characteristics and become what he describes as a pro-social psychopath.

“I have come to understand that humans are, by nature, complicated creatures,” he says.

“And to reduce our actions, motivations, desires and needs to absolutes is doing each of us a disservice.

“We are not simply good or evil, right or wrong, kind or vindictive, benign or dangerous.

“We are not simply the product of biology, either. Science can tell us only part of the story.”

Our genes, then, don’t determine our fate, but they have the power to send us in a certain evil direction.

How consoling that evil can be defeated by an even greater influence — a parent’s love. - Daily Mail

* The Psychopath Inside: A Neuroscientist’s Personal Journey Into The Dark Side Of The Brain by James Fallon (Current).