In my talks around the world, I often tell the story of Kaycee, a smart, resilient 14-year-old girl who meets a 17-year-old boy at a party. They end up having sex, something most parents don't want to think about at that age.
Kaycee thinks this cool, older boy is keen on her but discovers, before the party is even over, that he has done it for a bet with his mates. The experience is crushing and sends her life spinning out of control until, two years later, she is able to tell her parents and get help.
When we think about what we want for our kids, the experience of young love, the exploration of romance, friendship and sexuality, hopefully approached slowly and with care, is something we would wish to go well for them. Sadly, for today's teenagers, sex has become a source of much misery, and those who work with teens say it's a disaster area.
On the one hand, some things haven't changed. Some kids rush into sex, somewhat riskily, as they always did. Others go more slowly – a half of all young people don't become sexually active until their late teens or even early twenties.
But those who do are having an unhappy time – especially the girls. The explosion of pornography, and the unsupervised access that some boys have to it, and the fact that much of it is abusive or depicts humiliation of girls or women, which they are purported to like or enjoy, has miseducated a generation of boys about how sex works.
Girls need to hear from their mothers that sex is really great, when it's right.
And girls get the message from popular culture that they need to be sexy, from a very young age, to be liked; that this is their role in life. It's as if feminism never happened.
It's crucial that we teach our kids that porn and real-life lovemaking are very different. Happy sex is connected, vulnerable, trusting and goes best when you feel safe and cared about by the other person. It's not the "get her done" rush of two disconnected bodies.
Even in primary school, we need to let our kids know that others may show them yucky stuff, but that isn't what real love is like. Our girls need to know that their bodies belong to them, and they get to choose and to be in control.
They also need to hear from their mothers that sex is really great, when it's right. This positive message is known to actually slow girls' progress into sexual activity, as they don't settle for second-rate.
Both parents must tell boys to treat girls always with respect, and be absolutely sure never to pressure or invade her space without very clear consent. Schools need to teach this, too.
It's hard for mums and dads, but we need to step up. Our kids want us to talk about sex with them, even though they act embarrassed; it's a gap in their knowledge we need to fill. A happy sexuality is one of the Ten Things Girls Need Most; it's so important to ensure they have it.
Steve Biddulph is a psychologist and the author of Ten Things Girls Need Most. This is part of his weekly series for Fairfax Media.