June 06, 2009

MAOA and gang membership/weapon use

Comprehensive Psychiatry doi:10.1016/j.comppsych.2009.03.010

Monoamine oxidase A genotype is associated with gang membership and weapon use

Kevin M. Beaver et al.



A functional polymorphism in the promoter region of the monoamine oxidase A (MAOA) gene has been found to be associated with a broad range of antisocial phenotypes, including physical violence. At the same time, it is well known that gang members represent some of the most serious violent offenders. Even so, no research has ever examined the association between MAOA and gang membership.


The aim of this study is to examine the association between MAOA and gang membership and between MAOA and weapon use.


We examined the effects of MAOA by using a molecular genetic association research design.


A nonclinical sample was used in this study.


Participants were drawn from the National Longitudinal Study of Adolescent Health (1155 females, 1041 males).

Main Outcome Measures

The outcome measures of this study are gang membership and weapon use.


The low MAOA activity alleles conferred an increased risk of joining a gang and using a weapon in a fight for males but not for females. Moreover, among male gang members, those who used weapons in a fight were more likely to have a low MAOA activity allele when compared with male gang members who do not use weapons in a fight.


Male carriers of low MAOA activity alleles are at risk for becoming a gang member and, once a gang member, are at risk for using weapons in a fight.


1 comment:

Unknown said...

Very interesting study. I've never doubted that genes play a significant role in violent criminality, but much of that information is suppressed or researchers are afraid to do such controversial research. I've long thought in my mind about the genetic/environmental influences that could be used to predict or practically guarantee violent criminality:

1)Low IQ(but not too low)
2)Single parent home or raised in foster homes
3)Above average testosterone levels
5)High school drop out/school failure and/or learning disabilities
6)Unemployment/lack of job skills
7)Grew up in a violent community
8)Father(or mother, or mother's father) was a violent criminal, or grandfather, or great grandfather, or uncles or one or all of them(aggressive tendencies/high testosterone levels have a strong genetic component)
9)Lack of conscientiousness(also to some degree genetic)
10)Abused and/or neglected as a child
11)Drug and/or alcohol problems(genes again, possibly)
12)Wide face/skull - This tends to correlate with aggressive tendencies, and is sort of like a proxy measure of testosterone levels
13)Mental illness/head injury
14)And now low MAOA activity alleles(may explain in part how violent criminality runs in families)

A male with this combination of factors is very likely to become a violent criminal. I don't think it is a 90% chance, but it may come close to this or surpass this if a few more genetic or environmental factors are thrown in.