One in five girls have had an unwanted sexual experience, at their most extreme experiencing horrifying injuries from violent sex.
And up to 60 per cent of high school students have been in an emotionally or physically abusive relationship.
These are some of the shocking revelations in a study on adolescent relationship violence.
Author of the NZ Family Violence Clearinghouse paper, Dr Melanie Beres, is calling for action to prevent abusive relationships among teenagers. One third of young people reported being hit or harmed by a partner and 20 per cent of Women's Refuge cases involved women aged under 20.
"Adolescence is a key time where we learn about how to have intimate relationships," Beres said.
"If our introduction to relationships is around issues of power and control and emotional abuse this can influence later relationships in life"
Beres said gender norms had a lot to answer for. To change behaviour they need to be challenged.
"Boys are taught to be tough, strong and in control," the report stated.
"They are taught that they should want sex and it's their job to initiate and 'get' it.
"Girls are taught to be polite and to be nurturers by looking after the feelings of others. They are cautioned that being 'too sexual' is a risk for them because boys cannot control themselves."
She said this was obvious in the coverage of the Wellington College students who wrote about raping girls on Facebook.
"There was talk that they are good boys who made a mistake rather than looking at their behaviour and saying this is a problem, there's a bigger issue here.
"This is not just about these two individuals, this is actually about a social problem we have in the ways young men are taught to perceive young women and talk about young women."
In 2013/14 the Ministry of Social Development spent $21 million on primary prevention, which accounted for 1.5 per cent of the total spend.
Beres said more money should be directed at setting examples of healthy relationships and positive gender roles.
"If we are serious about solving this issue we need to put more resources into primary prevention to look at building healthy relationships rather than intervening when things are already pear shaped.
"It's about learning how to value other things in men and women."
A Ministry of Justice spokesman said prevention and reponse were integral aspects of every family violence initiative.
"Naturally, we want to prevent family violence happening in the first place, but we cannot shy away from the fact that it does happen, far too often. That's why agencies' responses are always geared to protect, prevent recurrence and support victims to move forward with their lives, free from fear."
Just over $8 million was spent in 2016/17 on eight prevention programmes - E Tu Whanau, It's Not OK, Pasefika Proud Campaign, Family Violence Response Coordination, Auckland Humanity Project, Jade Speaks Up, Shaken Baby (Power to Protect programme) and White Ribbon.
Women's Refuge principal adviser Ruth Macintyre-Bardell said the report echoed her organisation's observations. She had a medical professional tell her young women were coming in with horrific injuries, such as rectal prolapses, caused by violent sex.
Macintyre-Bardell believed this was due to the normalisation of pornography and girls not knowing what was okay and healthy.
She supported Beres' call for more funding for prevention. She said the information needed to be presented in a culturally appropriate, age-appropriate, meaningful way with dynamic facilitators.
"We're the ambulance at the bottom of the cliff so it'd be nice to invest in a fence at the top."
Children's Commissioner Judge Andrew Becroft said the biggest influence on adolescents were the people closest to them.
"We agree that it's a serious problem and that prevention at all levels is key to helping young people have positive relationships.
"We need to model the behaviour we want in the way we treat young people from a very early age, as well as in our relationships with each other."
An Education Review Office audit in 2007 found that most sexuality education programmes were not meeting students' needs effectively, the report stated.
The study used New Zealand and international literature as well as interviewing those working on the front lines of support services to draw its conclusions.
• Up to 60 per cent of high school students have been in an emotionally or physically abusive relationship.
• 29 per cent of New Zealand secondary students reported being hit or harmed by
another person in the previous year.
• 20 per cent of female and 9 per cent of male secondary school students reported having experienced unwanted sexual behaviour in the previous year. Most of the behaviour was by a boyfriend, girlfriend or friend.
• 21 per cent of women who stayed in women's refuges were aged 15-19 years.
• About 9 per cent of New Zealand secondary school students said they were attracted to people of the same-sex, or unsure of their sexual attraction, and up to 3 per cent identified as transgender or unsure of their gender identity.
• Compared with other New Zealanders, adolescents between the ages of 15 and 19 have the highest rates of intimate partner violence, according to the New Zealand Crime and Safety Survey.
• Intimate-partner violence is perpetrated by and against people from all communities, ethnic groups and socio-economic backgrounds, but marginalised groups are at higher risk.