ESSAY: I am a criminologist by training, which means that I make my living trying to better understand the causes of criminal behavior. My research specialty in particular is something my colleagues and I call biosocial criminology. What is that, you ask? The simplest way to answer that question is to clarify what it is not — biosocial criminology is not one thing. It encompasses various flavors of psychology, biology, genetics, and neuroscience all aimed in the direction of understanding why human beings engage in a host of disreputable, dangerous, aggressive, and, of course, illegal behaviors.
The logic for approaching the study of crime in this manner is simple. Human beings perpetrate criminal behavior and humans are biological creatures. Simple reasoning would require that biology should play some role in the production of crime. For decades, however, our traditional criminology colleagues disagreed with us. They sternly rejected the chain of thought that I just described and chided those of us who maintained that biology was important. Even now, doubts persist about the importance of biology for the study of crime.
While writing this, it struck me as ironic that an important father of modern criminology, Cesare Lombroso (Italian physician from over a century past), was one of the first scientists to proffer biologically tinged theories of crime. Although these theories were incorrect, they were key steps in the evolution of criminological science. But, as fate would have it, the very science birthed in part by the physician, a “biosocial criminologist”, would eventually grow hostile to biology. Lombroso and his arguments were caricatured, transformed into the laughing stock of the field . First year theory students (undergraduate and graduate) are now treated to an annual skewering of Lombroso. Everyone in the class has a nice chuckle at his expense and the discussion moves along to the “true” sociological wisdom that waits ahead in the semester.
In any situation where two sides of an argument are competing for the intellectual high ground, it is natural to ask who was right. A massive study  just published in the academic journal Nature Genetics synthesized 50 years worth of behavior genetics research and settled the issue nicely. I’ll distill the findings down: there is virtually no human trait untouched by genes.
Whether the question concerns why some are taller than others, why some are smarter than others, or why some are more psychiatrically disturbed than others, the answer is that genetic differences play a role. There have also been four separate reviews of the literature examining behavior genetic studies on the topic of criminal and antisocial behavior specifically [3,4,5,6]. The conclusions are precisely the same as those from the Nature study. The reason why some are more prone to crime than others has much to do with their genes. Do not bother lazily invoking explanations like poverty, parenting, neighborhood factors, and the like. Start with genes and then go from there.
At this point, I can already hear the critics chiming in about how I’ve glossed over every bit of important nuance. Where is the discussion of gene-environment interaction and gene expression? Why have I behaved like such a genetic determinist? Have I glossed over some nuance? To some degree, yes, but I have a good reason for doing so. The purpose of our discussion is not to delineate the intricacies of gene-environment interplay. More importantly, frivolous appeals to near meaningless “it’s both nature and nurture” type arguments serve no purpose. Behavior genetic models are designed to parse genetic and environmental influences on outcomes at the population level so it is entirely meaningful to talk about both separately. Do genes and environments (as well as multiple genes in the genome) interact to influence behavior? Yes. Does gene expression change across time as a result of environmental exposure and because of the regulatory functions of other genes? Yes. Are these vital components to explaining large swaths of human differences in violent, aggressive, and criminal forms of behavior? The evidence does not suggest it to this point, but there is more work to be done.