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Can Our Genes Determine If We're Cold-Blooded Killers?

Lindy Tolbert |
August 9, 2010 | 12:12 a.m. PDT

Staff Reporter

Lies.  Scheming.  Cheating.  Murder.

All words that, if strung together, would make an impressively stereotypical “Lifetime Original Movie” tagline.

But what else do they have in common, other than the obvious debauchery and moral ambiguity with which they are associated?

They all show patterns on PET brain scans.

Enter UC Irvine neuroscientist Jim Fallon: highly educated, well-respected family man who, for the past several years, has conducted brain scans on more than 70 documented psychopathic killers.

Fallon, far right, with his family.  Creative Commons
Fallon, far right, with his family. Creative Commons

The twist: Fallon, far right, now claims that, had he not had a blessed childhood, he himself would most likely be a killer, not unlike the murderers he studies.

So how does a well-established scientist resemble the meanest, roughest inmate at San Quentin?

Fallon says it’s because his brain is pre-disposed to violent behavior.

According to Fallon’s research, it all starts out in the orbital cortex, the area of the brain that controls a person’s ability to determine moral and ethical behavior, as well as control impulses.

This area is also responsible for the control of the amygdala, which monitors appetites and aggression.

Most sociopaths have low brain activity in the orbital cortex, which in turn can give free reign to the whims and desires of the amygdala.  

It’s not just brain activity that determines violent tendencies.  It’s genetics, too.

In his research, Fallon looked at the 12 known genes related to displays of aggression and identified a specific MAO-A (also known as monoamine oxidase A), or “warrior” gene, as the common link between killers. 

MAO-A regulates serotonin, a chemical in your brain that controls moods.  

Certain variations of the warrior gene are thought by scientists to be resistant to the calming effects of serotonin.

Fallon has startling amounts of this gene.  His family history even bespeaks the aggression inheritance theory. 

His great-grandfather, Thomas Cornell, was hanged in 1667 for murdering his mother.  Seven more murderers followed him in the Cornell http://online.wsj.com/article/SB125745788725531839.html)">family line. 

His distant cousin, the infamous Lizzie Borden, was accused of killing her father and stepmother with an ax in 1882 but was acquitted amid much controversy. 

So, by all rights, Fallon has the perfect genetic storm to be the newest Ted Bundy.

However, in spite of all his genetic pre-conditioning, Fallon has not turned into a killer, and no one else in his immediate family has gene patterns or brain activity like his.

Fallon family brain scans.
Fallon family brain scans.

He says he turned out normally because he had an excellent childhood and great family relations.

So is it nature that makes these murderers tick? Or is it nurture?

It appears to be a mixture of both. It can’t be simplified to one or the other.

There needs to be a mix of all three factors (genetics, brain patterns and/or damage, and a tumultuous upbringing) to be the ultimate breeding ground for violent and risky behavior. 

Claiming “genetics made me do it,” like we see in many courtroom procedurals, is just irresponsible. It’s trying to find a scapegoat, much like many people do when they have violent children.  It’s easier to blame video games than to think, “Maybe my child has a problem.”

Genetics do not determine how anyone chooses to behave. 

Fallon is the perfect example of this: If he’d had a bad childhood, he might have been a killer, but he didn’t. 

This just proves that it’s nurture that defines us. Genetics and brain patterns are the small push that tip us over the edge.

Life is all about choices.  Ultimately, we decide who we are and what we choose to become.

But then again...I had a happy childhood.


Reach reporter Lindy Tolbert here.



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