Genes, Violence, and Testing

The abstract of an article in Molecular Psychiatry entitled Genetic background of extreme violent behavior reads as follows:

In developed countries, the majority of all violent crime is committed by a small group of antisocial recidivistic offenders, but no genes have been shown to contribute to recidivistic violent offending or severe violent behavior, such as homicide. Our results, from two independent cohorts of Finnish prisoners, revealed that a monoamine oxidase A (MAOA) low-activity genotype (contributing to low dopamine turnover rate) as well as the CDH13 gene (coding for neuronal membrane adhesion protein) are associated with extremely violent behavior (at least 10 committed homicides, attempted homicides or batteries). No substantial signal was observed for either MAOA or CDH13 among non-violent offenders, indicating that findings were specific for violent offending, and not largely attributable to substance abuse or antisocial personality disorder. These results indicate both low monoamine metabolism and neuronal membrane dysfunction as plausible factors in the etiology of extreme criminal violent behavior, and imply that at least about 5–10% of all severe violent crime in Finland is attributable to the aforementioned MAOA and CDH13 genotypes.

Now, we are in the early phases of something that will be one day be termed a genetic revolution. Whatever is known about genetic influences on crime (or anything else, for that matter) pales in comparison to what will be known in a couple of decades. We may not be far from the point where a journal article tells us about eighteen, twenty or fifty three genotypes that explain 85% or 90% or 99.9% of all severe violent crime in Finland. So it pays to think about the big questions early.

And this abstract raises one big question: what if we have the tools to detect those most likely to commit the worst of the worst violent crimes? Biology is not destiny, and some percentage of people who have a tendency toward violence (a big percentage? a small percentage?) may have the fortitude or wherewithal not to follow through. Or to avoid getting caught, which legally amounts to the same thing, though not for the victim(s). That makes widespread testing for these traits problematic, particularly if it were mandatory.

On the other hand, if the genetic link with violence turns out to be sufficiently strong, one can imagine situations arising where people formed associations whose membership is based on disclosure of results of tests for specific genetic traits. I’m guessing parents of young children would join en masse. Exactly what those voluntary associations might look like, and whether they could actually exclude those who “failed” or “tested positive” for the wrong thing might be something future courts will be considering. As long as nobody was being coerced, such situations might be deemed legal. All sorts of things seem to be legal depending on the context. For instance, age discrimination is illegal when it comes to jobs, but seems to be perfectly acceptable when it comes to determining who can live in a retirement community.

One additional tidbit of information worth considering. Despite a number of silly articles in the early oughts that violated all semblance of common sense, not to mention some insane drivel coming out of a few corners of academia today, increased levels of testosterone are associated with aggressive behavior. Testosterone, of course, happens to be the primary male sex hormone, and that’s a big part of the reason that in just about every human society, at just about every point in time, males have been the perpetrators of the overwhelming majority of the violence. (It goes for other primates too.)

Anyway, what can, what should, and what will be done may be three separate questions in a few decades. That’s all too far out for me to have a good idea of the shape of what is to come, but it will tremendously affect society and how we live.  What are your thoughts?

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