MAOA and violence

By Razib Khan | June 10, 2009 10:35 am

The locus MAOA pops up every year or so in a study which attempts to correlate variation in these region with behavior. In particular, anti-social or pathological behavior. So another one is out, Monoamine oxidase A genotype is associated with 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.

Here’s a regression table which shows the main results:
This figure in particular is striking:

The MAOA variant is on the X chromosome, so obviously the genetic architecture is different for males and females (males have only one X). They didn’t find much for females in this study. Another way to restate the study findings is that males with the low MAOA genotype MAOA genotype were 1.94 times more likely to be gang members, and they were 1.82 times more likely to have used a weapon in a fight.
Cite: Monoamine oxidase A genotype is associated with gang membership and
weapon use
, Kevin M. Beaver, Matt DeLisi, Michael G. Vaughn and J.C. Barn, doi:10.1016/j.comppsych.2009.03.010


Comments (2)

  1. bioIgnoramus

    Less than twice as likely; not quite The Berserker Gene, then?

  2. joe

    This is interesting stuff. Do you know of any studies on how MAOA varies by race? Is that easy to check out with hapmap?


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Gene Expression

This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at


See More


RSS Razib’s Pinboard

Edifying books

Collapse bottom bar