Only 9 per cent of Asian families had one parent with at least one child under 18 compared with 28 per cent of Maori.
Of the children abused by age two, only 4.2 per cent were Asian compared with 60.9 Maori, 53.2 per cent NZ European and 21.7 per cent Pacific. Some children had multiple ethnic groups listed meaning the percentages did not total 100 per cent.
McCoskrie said the benefits of children being raised by married parents could not be ignored.
However, whenever marriage was promoted, it was seen as an attack on solo or divorced parents, he said.
"In virtually every category that social science has measured, children and adults do better when parents get married and stayed married - provided there is no presence of high conflict or violence."
The report analysed trends, based on Government research, in maltreatment, ethnic groups and family structure dating back from 1967, which is when there was a decline in the marriage rate.
"The research shows it's the presence of a biological father that generally, not always, protects children and it is marriage that significantly raises the chance that he will remain on the scene," McCroskie said.
Co-habited parents were four to five times more likely to separate by the time their child turned 5 than those who were married.
He said the Government needed to stop worrying offending people and instead focusing on the promotion of marriage and preventing marriage breakdowns. More research into married families was also needed in NZ.
"Even to say you want to encourage a marriage culture will get opposition but you have to ask yourself, what is more important. Is it the political correctness or protecting kids?
Report author Lindsay Mitchell, whose earlier research also identified a link between family structures and child poverty, said there were certain family set-ups where children were more vulnerable.
"In the same way discussion about child poverty ignore the elephant in the room - family structure - so do analyses of the incidence of child abuse."
The report also found a misconception around men predominately being the abusers as the figures showed men were responsible for 60 per cent of physical and sexual abuse, while women were more likely to neglect.