Design
We examined the effects of MAOA by using a molecular genetic association research design.
Setting
A nonclinical sample was used in this study.
Participants
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.
Results
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.
Conclusions
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.