As Kim Dungey reports, there are some who would still rather not.
"It's hard", says Dunedin mum Sharon* on the subject of talking to her teen about sex.
"You don't want to encourage it but you don't want to stick your head in the sand either."
Until recently, Sharon had managed to "steer" her daughter away from sexual activity.
But when she was 15, she agreed to her going on the contraceptive pill.
"I suddenly realised the inevitability of what was likely to happen and that if I left it up to her and her boyfriend, there was a higher likelihood of a teenage pregnancy," she explains.
"It's about feeling disappointed and sad but also realising you've got to step outside what you would like and deal with what the situation actually is."
Sharon says her daughter is a good student and not at all promiscuous, just "getting into things" earlier than she would have. The situation she describes is not unusual.
Sex education is a subject that divides us. Some are grateful schools cover it while others believe it should be left to parents to pass on "family values".
Sharon recalls her own "sex education" consisted of her mother giving her a book about sex, in a brown-paper envelope, and telling her to come to her with any questions.
"I learned most of it from hearing stories at school."
But she knows her daughter is growing up in a different world. Young people are bombarded by sexually explicit material and some engage in sexting - the act of sending sexually explicit messages or photos by phone.
"All this is going on and then they sit down and watch Hannah Montana or SpongeBob SquarePants. They're not in an emotional space to cope with it."
Earlier onset of puberty means girls are becoming "moody and hormonal" younger, she adds: "You feel that they're growing up too soon".
"The big fear with me is pregnancy ... because it can happen so easily."
Yet she also acknowledges adults are often so busy trying to avoid a teen pregnancy that they do not talk to young people about relationships.
"They get all the mechanics ... But there's that emotional, intangible thing that they're not getting enough of - that it's OK to say `no' and OK to say 'not just yet'."
The sensitive nature of the issue was highlighted last month when Family Planning introduced a new resource for primary teachers that had been given a trial in schools such as Dunedin's Tahuna Normal Intermediate.
The launch of "The Sexuality Road" upset the conservative lobby group, Family First, which told Family Planning to "butt out" and leave sex education to parents.
National director Bob McCoskrie said the current approach of comprehensive sex education and "use a condom" had been a spectacular failure, and the biggest protective factors for coping with puberty and sexual involvement were married parents, family values, parental supervision, and parental expectations for behaviour.
The Family Planning resource is aimed at younger children because research shows they are entering puberty earlier - the average age is between 9 and 14 for girls, and between 11 and 16 for boys.
Family Planning argues sex education that works starts early, before young people reach puberty and have developed established patterns of behaviour.
Dunedin Family Planning health promoter Gayna McConnell, who came up with the concept the "Sexuality Road" resource is based on, says New Zealand should look to the Netherlands, whose teen pregnancy and teen abortion rates are among the lowest in the developed world.
There, sex education is comprehensive and taught from a younger age, adolescent sexuality is normalised, and parents assume that teenagers can self-regulate their sexual development.
Instead, she says, we follow the example of the United States, where adolescent sexuality is dramatised and parents assume that teens can't control their raging hormones or be trusted to make their own decisions.
A silence about sexual issues is reflected in our statistics, which show young New Zealanders have sex earlier and in many cases with more partners than their overseas counterparts, she says.
Among developed countries, we are second only to the United States in teenage pregnancy rates.
Although about 54% of New Zealand adolescents are sexually active by the time they leave school, young people receive little guidance on how to embark on this aspect of their lives positively.
Sex education - compulsory since 2001 - is still delivered comprehensively in only 20% of schools and many parents are uncomfortable talking about such issues.
Young people are "left to work it out for themselves" and often follow stereotypical roles that leave them disempowered and unprotected.
Girls learn to be sexually available but not sexually in charge, while boys learn they should want sex and always be ready for it.
This, combined with alcohol and a lack of skills to deal with peer pressure or to negotiate limits, means many young people have negative rather than positive sexual experiences.
"It's why we have a culture where a lot of young people are having unsafe party sex," Ms McConnell says.
The resource does cover the pleasure of sex but she says most people don't.
"We're scared to tell them the whole story. We still pretend sex is about reproduction."
There is no evidence that comprehensive sex education leads to young people engaging in sex earlier, she says. There is evidence to the contrary.
• Many teens say nobody has really talked to them about sexual issues, other than about avoiding pregnancy, she adds, pointing to the work of Dr Louisa Allen, of Auckland University.
Dr Allen's research showed that young people wanted their sexuality to be seen as a positive part of youthful identity rather than a problem to be managed.
They wanted to be recognised as legitimate sexual agents with the ability to make their own sexual decisions, and wanted sex education that was more explicit and "real life".
Last year, a top scientist called for a coherent, integrated approach to sex education to help children cope with the early onset of puberty, a situation he described as an emerging national crisis.
Liggins Institute director Professor Peter Gluckman was reported as saying sex education had to become mainstream, not something only for the phys-ed teacher.
While children were maturing earlier physically, the wisdom and judgement pathways in their brains did not fully develop until they were 25 or 30.
The extent of this "mismatch" was unique in history, leaving today's children with a challenge that no other generation had faced.
Yet, a 2006 stocktake by the Education Review Office found most schools were failing to meet pupils' needs in sex-education lessons.
It found a pattern across some schools of sexuality education being taught in isolation to other subjects, with little or no meaningful assessment of pupils' needs, inadequate resources and teachers who were not well-prepared to teach the topic.
The government department says sex education programmes should treat delaying sexual intercourse as a priority but should also focus on safe sexual practices.
Boards of trustees must consult with their communities at least every two years about how the subject will be taught.
The lessons are compulsory up to and including year 10, though some pupils are exempted on religious and cultural grounds.
Ms McConnell says lessons as currently taught might be delivered by a phys-ed teacher, a science teacher, a school counsellor or an outside agency, all using different resources.
Some schools do the ideal 10 hours or more per year but for others, it is not a priority.
"Most schools want to do better but it comes down to time, staff turnover and the school culture."
Parents often think they have talked about sex much more than their children say they have.
"The reason it's hard [for parents] is because we learned from our parents and they learned from their parents. These taboos run deep ...
"Parents need to be talking a whole lot more."
To Sharon*, it seems that puberty is often shrouded in talk about bad skin and period pain and we "dance" around the issue of sex.
But that topic could not be avoided this year when her daughter became more serious about boys.
"You can see it. It's almost tangible," she says.
"And the reality hit me that as much as boys want to have sex, girls do too."
* Name changed at request.
Bombarded from all sides
Child advocates criticised a risque range of baby clothes last month as another example of the sexualisation of children.
The T-shirts in Cotton On Kids' New Zealand stores feature slogans such as "The condom broke" and "I'm living proof my mum is easy".
Child advocates say they exploit children for adults' entertainment and should be withdrawn.
On another occasion, World produced children's T-shirts with the words, "Future Porn Star".
As debate continues about sex education in schools, it's clear children are getting messages about sex from other sources and at younger ages.
Of particular concern to some is the sexualisation of "tweenies" - youngsters between early childhood and the teenage years - via the internet, magazines, clothes, music and television.
Critics link overtly sexual clothes, computer games and pop lyrics with early sexual activity and paedophilia, arguing that girls in particular are encouraged to take on a sexy appearance without being aware of the implications.
A 2007 report by the American Psychological Association also linked the proliferation of sexualised images of girls and young women in advertising and the media with eating disorders, low self-esteem and depression.
Closer to home, a 2008 study of 8- to 12-year-old girls by Canterbury University student Lorie Clark found many of them wanted to wear padded bras, sexy underwear, boob tubes, miniskirts and high-heeled shoes.
University of Otago sociology lecturer Lesley Procter says young girls dressing up and trying to be older than they are is part of life but the marketing of products such as Bratz dolls, which come in miniskirts and fishnet stockings, and music videos is "more pernicious, more subliminal and more serious in terms of individuals feeling pressured to conform".
"I've walked through clothing stores and seen micro-minis and very skimpy halter tops for 4-, 5- and 6-year-olds ... Yes, they want to copy their parents and copy what they've seen on TV. But those clothes can send a sexual message when worn by adults so what does it mean when they're worn by children?"
In their book So Sexy So Soon: The New Sexualised Childhood and What Parents Can Do to Protect Their Kids, Jean Kilbourne and Diane Levin argue it's not that children are learning about sex, it's what they are learning, the age at which they're learning it, and who's teaching them.
"Both boys and girls are routinely exposed to images of sexual behaviour devoid of emotions, attachment or consequences ... They learn that sex is often linked to violence.
"And they learn to associate physical appearance and buying the right products not only with being sexy but also with being successful as a person."
Others see the T-shirts and other pop-culture images as harmless fun.
They say children who don't know about sex suffer when it comes to fitting in and giving it taboo status will only make it a "forbidden pleasure".
Ms McConnell says young people watch Shortland Street and raunchy music videos but no-one is talking to them about it.
"We can't stop the music videos, the clothes that are available or the Bratz dolls. And to a degree, it's just going to get worse.
"But as parents, aunties, uncles and teachers, we can talk to our children about whether they think people really act that way," McConnell says.
"We can help them make sense of it."
