Speaking at a genetics conference in Australia, Rod Lea said that Maori men were twice as likely as European men to carry mono amine oxidase, describing it as a "striking over-representation" of what has been described as the warrior gene.
Media reports of Lea's findings have outraged Maori leaders who said they only reinforced "Once Were Warriors" cultural stereotypes, a reference to a harrowing 1994 movie about domestic violence in poor Maori families.
"I've been asked by reporters whether this gene is the reason why we're a violent race, why we feature so highly in criminality rates, that we're predisposed towards aggression," Maori Party co-leader Tariana Turia said in a statement.
"Once were gardeners, once were astronomers, once were philosophers, once were lovers," she said.
Lea, a genetic epidemiologist at the Institute of Environmental Science and Research in Wellington, the New Zealand capital, said the gene had also been linked to such risk-taking behaviour as smoking and gambling.
"I believe this gene has an influence on behaviour of humans in general, but I also believe that the influence is rather small," Lea told New Zealand's National Radio on Wednesday.
"We have to be clear that behavioural traits such as susceptibility to addiction, aggressive behaviour, risk taking, all those sort of things, are extremely complex and they are due to numerous factors including non-genetic environmental factors like upbringing and other lifestyle factors," he said.
Maori lawmaker Hone Harawira said he had been hearing similar descriptions for decades about New Zealand's indigenous people, who make up about eight per cent of the 4.1 million population.
"I've stopped listening to all that sort of carry on," Harawira said.
New Zealand's domestic violence problem, described by a government report as endemic and shameful, was highlighted by the deaths of three-month old Maori twins in Auckland, the nation's largest city, in June.
"We have to be clear that behavioural traits... are extremely complex and they are due to numerous factors including non-genetic environmental factors like upbringing and other lifestyle factors"
Rod Lea, Institute of Environmental Science and Research, Wellington
Chris and Cru Kahui had both suffered severe head injuries, but their Maori family has refused to cooperate with police.
Helen Clark, the New Zealand prime minister, described the Kahui twins' family as a "'Once Were Warriors' type family".
A UNICEF report last month found that between 18,000 and 35,000 children are exposed to domestic violence each year.
The problem is so common that most New Zealanders know a child who has witnessed violence at home, it said.
Government figures show that Maori children under five years old are being admitted to hospital with "intentional injury" at twice the rate of other ethnic groups.