According to New Zealand researche, a genetic epidemiologist at Environmental Science and Research, Dr Rod Lea and his colleagues, Maori men have a "striking over-representation" of monoamine oxidase, often referred to as the warrior gene, which is said to be strongly associated with aggressive behaviour.
Maori Party co-leader Tariana Turia dismissed any such suggestions of Maoris being genetically inclined to violence and criminal acts.
She said, 'This is incredible. I realise that violence is an issue to us, but there are very common factors as well with violence which are not really related to race.'
While the Maoris' predisposition to alcoholism was common knowledge, Turia said that it was a big leap to include violent tendencies in that.
She said, "I've never felt criminally inclined myself and I'm very pleased to say that the majority of Maori people don't feel criminally inclined."
Author of Once Were Warriors, Alan Duff said the theories put forth by Leacould be repudiated by examples of Maori being raised in non-Maori environments who became super-violent or non-violent.
He said, "I've always had a bit of a dilemma about the nature-nurture thing.I would say that the last thing that we need is another excuse or another reason for Maori dominating in the violence stakes and all the bad stats."
The director of the Christchurch School of Medicine's Maori Indigenous Health Unit, Suzanne Pitama, said, 'Every person is a result of complex factors and I think that it's too easy to kind of just blame one thing. There are a whole lot of things that contribute to violence in Maori communities'
Lea stated that unpublished studies had proved that Maori had the highest prevalence of this strength gene which was discovered by United States researchers but was never linked to an ethnic group.
Lea said this could also explain how Maori managed to migrate across the Pacific and survive as they had, said Lea. He said, "Obviously, this means they are going to be more aggressive and violent and more likely to get involved in risk-taking behaviour like gambling.It is controversial because it has implications suggesting links with criminality among Maori people."
He added,"I think there is a link. It definitely predisposes people to be more likely to be criminals and engage in that type of behaviour as they grow older."
Lea theorized that non-genetic factors might also be at play.
He said, 'There is lots of lifestyle, upbringing-related exposures that could be relevant here, so obviously the gene won't automatically make you a criminal.'
According to Lea the same gene was also linked to high rates of alcoholism and smoking among Maori.
He said,"In terms of alcohol-metabolising genes, we've found that Maori have a unique genetic signature. That influences their drinking behaviour, so they're much more likely to binge-drink than other groups, which are more likely to moderate their drinking."
Another gene, referred to as the thrifty gene, linked to obesity among the Maori was also studied. The gene is believed to be related to energy conservation and responsible for Maori making it to New Zealand shores in the first place.
Lea said,"They specifically conserved their energy for long voyages and because of this survived, bringing their genes with them."
Although the researchers have not yet entirely understood the role of lifestyle factors, they believed ancestral genetics played a vital role. Thousands of DNA samples have been collected from Maori to investigate these traits.
Lea added, "With Maori, it's easier to find the genes than it is in the broader Caucasian population, so it's a great case study."