Back in high school I was reading every available book and article about science, preferring those on biology and evolution. One problem was, when conflicting opinions were proposed, whom should I believe? I did not have the knowledge to judge on my own the scientific merit of a statement. This was a big part of my decision to study biochemistry. Now I am in a position to use my professional experience and knowledge to read an article and judge, verify new information and follow up interesting facts in the original literature.

A 2003 ‘Column One’ article by Robert Lee Hotz and John Johnson in the Los Angeles Times titled ‘Behavior may leave a mark on genes’ forcefully reminded me of this uneasiness I felt then and I tried to think what I would learn from this article about the relationship between genes and behavior without my training as a biochemist. At first, I thought this is one of these occasional revivals of Lamarckian ideas. Turns out, the article is an excellent piece on the nature-nurture debate using the Weaver family’s (father and son) brutal history of serial killings. But there are a few aspects in the article that reminded me of my high school days and the questions I had about what to believe and how to verify facts. One sentence sticks out that made me think. It read: “Until recently, the most powerful tool to analyze behavior and heredity was statistics, not molecular biology or neuroscience”. A sentence like this one makes my scientific mind cringe, because of the implication that there is statistics and then there are molecular biology and neuroscience. This of course compares apples with oranges. What the sentence is really saying is that until recently, statistical analysis of behavior of genetically distinguishable groups was the only tool to show that differences in behavior can be correlated to a genetic component (the nature of which remains elusive, but that is where molecular biology comes in). Now, molecular biology (genes and gene expression) and neuroscience (e.g. brain scans) add a biological explanation, or as I prefer to say mechanism, of these differences, i.e., they illustrate a causative link between specific genes and behavior, and that maybe, just maybe, this link is a two-way street. To reach those conclusions, however, molecular biologists and neuroscientists depend as much on statistics as behaviorists. Without statistical evaluation, both a gene expression pattern and false color images of oxygen flow in the brain would be meaningless. The novel interesting findings, and this is what this article is all about, is to explain the scientific evidence corroborating the suspected influence social interaction has on which genes are active at any given time during our lives. These activity patterns depend on which genes are present in the first place (heredity). Which ones of the available genes are actually used (heredity and environment) will transcend as behavior. Some genes are more influential than others, but no gene alone shapes a specific trait.

The effect of social interactions on usage of genes is most important during the formative years. Evidence shows that usage is fixed early on in live and usually not changed later on. This is way we call childhood ‘formative’. Later on, changing behavior is very difficult, but can be accomplished with will and determination, and help from others. What we call learning, is very likely a reprogramming of gene activity in the brain. Not all areas of the brain will or can be affected in the same way. This, too, is likely to be genetically determined hinting at the many layers of interaction between genes and their environment

So in my view, and if the genetic underpinnings explained in this article are ‘true’, the older Weaver was right in saying that ‘everyone is capable of killing someone’, because the genetic heritage of Homo sapiens violent behavior slumbers in all of us, occasionally awakened and epigenetically (gene usage) fixed by social interactions. He is of course wrong if he means that everyone will act upon their fantasies. We don’t know what exactly it takes for a particular person the follow through on violent thoughts. For me, realizing that so many genes and environmental factors influence our human nature and that we are all somehow different is the beauty of our biology and the driving force behind evolution. Examples like the Weavers, while instructive, are anecdotal and don’t prove anything (e.g. lack of statistical power). The resilience of violent behavior and the fact that it is part of our human biological inheritance (in a ‘positive’ i.e., socially accepted way related to self-defense or the killing of animals for food) is mirrored in thousands of years of criminal law – deterrence of crime using capital punishment, torture, mutilation – which by all account have not and never will deter future killings, wars, or indifference to the suffering of others.

And finally, what about the future of predicting and preventing violence? The answer cannot come from labeling people as in some way genetically predetermined, lest we are willing to incarcerate all men, or castrate them (sorry not me, I am one of the good ones), as men are historically more violent than women. But which men? Not all men are created equal, biologically speaking. Should we trash our constitution based on DNA evidence? The important question is what it means to be predisposed to be or do something? Nothing is certain in live except death. We have learned to live with uncertainty and cannot eliminate it. As for solutions, while reading some of the scientists answers using genetic or other scientific statistical analysis as a means to control people’s lives, I’d prefer the good old moral values of religion, the duty to strive toward goodness, all the while keeping in mind that all humans are both good and evil. We need to suppress the urge to punish people for what they might do, instead of what they have done. Because one day, you the reader, will be deemed capable of killing based on a yet unpublished study of a risk factor analysis rather than how you conducted your life. Thus, if genetic risk factor analysis of behavior should become reliable, let it be used to help the afflicted before we punish the innocent.

Lukas Buehler, November 21, 2010

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