Nature vs. Nurture: Is there a crime gene?

What factors contribute to someone being a criminal? How does a child raised in a loving adoptive family grow up to become a criminal? The response to this question varies depending on a number of variables, including the genetic makeup of the person and the parent's approach to raising a child. In society, the majority of the focus has gone to social determinants or environmental variables. One example is the socio-economic situation of the child. This is frequently investigated when criminal conduct occurs. However, social characteristics may not be enough to explain the large variety of criminal conduct seen. This is when we can turn to the possibility of genetics creating a predisposition in humans to become criminals. 

Figure 1. Double helix with handcuffs signifying a gene for criminality

Firstly, I'd like to clear up the misconception that there are one or two specific "crime genes". It is difficult to believe that a single gene codes for criminal behavior; instead, it is more likely that numerous genes combine to enhance the likelihood of criminal behavior. Furthermore, additional behavioral features linked to criminal behavior, such as impulsivity and sensation-seeking behaviors, are believed to be linked to hereditary variables. 

However, individuals do not become criminals due to their genes alone. Furthermore, a genetic tendency to particular conduct does not imply that a person would become a criminal. The idea that humans are predisposed to partaking in certain behaviors ignores significant environmental elements that are likely to mitigate the genetic-crime relationship. Positive family raising conditions, for example, may reduce or eliminate the expression of a genetic probability towards a particular behavior. A negative familial upbringing may lead to a hereditary vulnerability. This shows that genes and the environment work together to either increase or decrease the chance of certain outcomes like criminality.

However, there are two genes linked to violent crime which were discovered in a genomic investigation of over 900 offenders in Finland. Those who have the genes were thirteen times more likely to have a history of violent behavior. Individuals with these genotypes are responsible for at least 5-10% of all violent crimes in Finland, according to the study's authors, who published their findings in the journal Molecular Psychiatry. However, they cautioned that the genes could not be used to identify offenders. Many more genes could be involved in aggressive conduct, and environmental factors are also thought to play a role. Even if a person possesses a "high-risk combination" of these genes, the majority of people would never commit a crime, according to lead scientist Jari Tiihonen of Sweden's Karolinska Institute.  Jari Tiihonen quotes, "Committing a severe, violent crime is extremely rare in the general population. So even though the relative risk would be increased, the absolute risk is very low", he tells BBC. The study is the first of its kind to look at the genetic makeup of so many violent criminals and created promising results, however we still can not excuse violent criminals due to their genetic makeup.

The first of the two genes is called the "warrior gene"  or the MAOA gene because of its link to violent behavior. The MAOA protein breaks down neurotransmitters. To support the connection between the MAOA gene and violent criminal behaviors the study evaluated each criminal and separated them into a profile based on their crimes. This separation classified them as violent or non-violent. The 78 people who met the category of "very violent offender" committed a total of 1,154 murders, manslaughters, attempted homicides, and battery. It is no coincidence that those 78 offenders had the strongest link between MAOA genes and previous violent behavior. 

The second gene is called CDH13 a variant of cadherin 13. Cadherin-13, a member of the cadherin family of cell adhesion molecules, has been identified as a risk gene for ADHD and a variety of disorders. For example, depression, substance abuse, autism spectrum disorder, and violent behavior. Cadherin-13 is an unusual member of the cadherin superfamily, often known as T-cadherin or H-cadherin. Furthermore, ADHD is a disorder that is associated strongly with violent crime. 

Figure 2. A double helix model

To summarize, in my opinion, a person's genetic information should have no influence on the outcome of a criminal trial. A person's mental capacity can be influenced by a variety of factors. The only thing that matters when it comes to a criminal trial is the individual's mental capacity to comprehend the implications of their actions and their ability to manage their own behavior. It is very important to realize that there are not just one or two genes that can be factored in violence or criminality. We are all products of heredity and the environment we grow up in, but I do not believe this deprives us of free will or the ability to choose and understand the difference between good and evil.