There is a small group of parents, religious groups and predominantly Tory politicians who swing into action every time sex education is mentioned. Today, as the Commons education committee released its report into the subject, they were at it again.
"Parents are the primary educators of their children, they are natural sex educators of their children and they are the experts on their own children," Antonia Tully of Safe at School said. "Parents constantly find themselves having to battle with schools in order to protect their children from inappropriate sex education."
The central problem with this argument is that children cannot be protected from inappropriate material. Online pornography is now so prevalent no child content filter can stop a teenager getting hold of it if they are determined, and generally speaking teenagers are when it comes to pornography.
As Graham Ritchie, principal policy adviser for the children's commissioner, told the committee:
"We know that it affects them. It affects young women and their body image - self-objectification. It affects young men and the expectations that they have of sexual partners. Therefore, it is incumbent on schools to address that issue and talk with young people about it."
Among young girls there are concerning signs they are becoming tolerant of abusive behaviour. Two-fifths of girls said it was acceptable for a partner to make them say where they are all the time and 17% said it was acceptable for their partner to send photos or videos of them without their permission. One in five thought it was OK for them to tell them what to wear.
The internet and digital communication are affecting young people's ideas about consent and healthy relationships
And then there is the spectre of child abuse. As Alison Hadley, who led the government's successful teenage pregnancy strategy, said, school classes can help protect schools against predators.
"If you have really good, comprehensive sex and relationships education, you talk about consent in a meaningful way with young people. You tell them about age gaps and predatory behaviours, so they start to recognise that. If you are not giving them any ammunition to understand these things, no wonder they are ending up in very dangerous situations."
The debate over sex education in schools is not really about whether it's appropriate or not. The world is full of inappropriate material and behaviour. It's about whether we arm children with the intellectual and emotional tools to stand a chance in it.
But even as today's report was being published, the Daily Mail's front page was whipping up outrage. "NHS gives condoms to pupil aged 13," it screamed. The Mail front page comes from the same emotional place as the Christian groups against sex education – they both approach the world as they would like it to be, rather than as it is. That is not a luxury children themselves have.
And yet the movement against sex education has been remarkably successful, both in Westminster and locally. One primary school said it could not provide the classes because their chair of governors was an elderly priest and "they could not possibly discuss it with him".
The Christian Institute convinced many politicians with claims that primary school sex education classes "often contain graphic material that is highly unsuitable for classroom use" and that "some material is so explicit that if it were shown by an adult to a child in a non-school setting, it would be regarded by many as child abuse".
It was all nonsense. Janet Palmer, national lead for personal, social, health and economic education at Ofsted, said the watchdog had not encountered inappropriate materials.
"What we did find usually were materials that were too little too late - materials that were being used where children were asking these questions probably two or three years before and they were not being answered. We did not come across anything that we would say was too explicit for children who were too young."
These campaigns seem to have had some effect on the government. In 2009, Alisdair Macdonald's independent review recommended making personal, social, health and economic education part of the national curriculum. The proposal was lost at the end of the parliament. When the Department for Education launched a new review in 2011, it was off the table. At its conclusion, it was decided it would remain non-statutory and that "teachers are best placed to understand the needs of their pupils and do not need additional central prescription".
Teenagers can often find online porn regardless of family filters
A little later, amendments were proposed in the Lords to make sex education compulsory. It was batted away, but Lord Nash, parliamentary under-secretary for schools, wrote to its supporters setting out the steps the government was taking to improve "expectations of high quality" teaching on the subject.
They were not worth much. It's not as if the coalition government is actively against sex education. You just get the sense their heart isn't in it.
While there was a mention of personal, social, health and economic education in the introduction to the national curriculum, other promises were rather weaker. Nash said an email would be sent to all schools with "a very prominent reminder" that they must publish their provision for the classes. But when the education committee got hold of the email, they found it made no mention of it.
As the education committee found:
"The government's current strategy for improving [sex ed] in schools is weak, and the recent actions taken by the government are insufficient to make much difference."
The committee found personal, social, health and economic education needed improvement in 40% of schools. This is a significant decline since 2010, when provision was good or outstanding in three-quarters of schools surveyed.
Young people consistently report the sex ed they receive is inadequate. There is a dearth of suitably trained teachers or time devoted to the subject.
We know the demand is there. Ninety-eight per cent of Mumsnet users said they were happy for their children to receive sex ed. The National Association of Head Teachers reported that 88% of parents of school-aged children wanted it to be compulsory. A petition led by the Everyday Sexism Project and the End Violence Against Women Coalition calling for classes on sexual consent, respectful relationships and online pornography received over 36,000 signatures. Girlguiding UK said young girls "want and need" the classes.
We just need the supply. And for that we need a government which does not get embarrassed discussing it, or opt instead for technologically illiterate solutions like internet filtering systems. The sooner sex education is put on the national curriculum and given the funding and training it deserves, the sooner we'll have protected our children from the dangers of the internet age.