Is criminality genetic? MAOA-3R


I'm a credit to my gender
PREMO Member
Some studies argue that certain genes are a good predictor of future criminality.

The MAOA warrior gene was the first candidate gene to be linked to antisocial behavior, identified in 1993 in a large Dutch family that was notorious for violence. A geneticist called Rod Lea reported that the MAOA-3R mutation was more common in the violent indigenous Maori population of New Zealand than in caucasian males (56% vs 34%). Lea went on to link this gene to a whole host of undesirable traits, such as violence, aggression, risk-taking and gambling/addiction.
Beaver (2013) conducted research into MAOA-3R in America and found that it increased the likelihood of an individual joining a violent gang.

Studies have found differences in the frequency distribution of variants of the MAOA gene between ethnic groups: of the participants, 59% of Black men, 54% of Chinese men, 56% of Maori men, and 34% of Caucasian men carried the 3R allele

According to a large meta-analysis in 2014, the 3R allele had a small main effect on aggression and antisocial behavior, even in the absence of other interaction factors

if there was a mutation to the gene that is involved in the process of promoting or inhibiting MAO enzymes, it could affect a person's personality or behaviour and could therefore make them more prone to aggression.

Scientists say it's the "warrior gene," a controversial name for a genetic variation that research has shown to have an ugly side tied to violence, risk taking and aggression.Found in one-in-three western men, it is literally a shorter, less active version of a gene allele on the X chromosome known as Monoaminine oxidrase A gene.
"In many, many studies it appears implicated in behaviors that look like they're related to physical aggression or some kind of conduct disorder,"

The genetic variant is located on the X chromosome of DNA and because men only have one X chromosome the connections to violence are seen more readily in men. Studies have also linked the variant to gambling, gang membership and weapon use.


Up. Identified. Lase. Fire. On the way.
PREMO Member
This stuff is pretty cool (and in the wheelhouse of my current pursuit; though at a very simple level).

We have to be careful not to oversimplify. No single gene is responsible for anything. Instead, it is almost always a complex interaction of genes and environment. Ref #1 gets it quite correct, I think: "It is important to note, however, that current research indicates that social environment, specifically abuse during childhood, appears to be a necessary requirement for the faulty version of this gene to trigger violent tendencies." I would add, "probably not the only one, either."

As such, I tend to favor the "Swiss cheese" model used in addictions counseling. This model essentially says there are multiple "requirements" for something to happen (the various slices) and that the holes in each slice must line up at least partially for an addiction to switch on. Same sort of thing is research-supported in auto-immune diseases, for example. That's, for instance, one reason with things like addictions or autoimmune you often also hear "co-morbid": complicated to treat. So if it's complicated to treat it's probably complicated in origin.

The whole MAOA "thing" is fascinating. Along with TCAs, MOA-x inhibitors were the first generation antidepressants (and meds for other neurological conditions, such as biploar or Parkinson's). So clearly the various types of MOA-x function at a very important level in the brain chemistry. So important that their activities were probably fairly easy to "find" and a natural focus for researchers to try to assign correlation. Anyway, my point is that it's more complicated than that so that not everyone with MOA-x issues will suffer from depression or violent tendencies. As someone once said, this sort of thing is descriptive not prescriptive.

There are, of course, very important socio-political-legal implications when we talk "genes," but that's a discussion for another time.

Thanks for the post; gave me an opportunity to muse aloud.

--- End of line (MCP)