The Scouts' motto has long been "Be prepared". But with no mention of sex education in the organisation, scouts have been left ill-equipped to deal with this vital aspect of growing up. All that is about to change: the Scouts have just announced that they will be offering advice on sex and relationships to their members.

Family pressure groups and Widdicombites are horrified. They say that such advice is simply "not appropriate" for the Scouts. But for an organisation that claims to be about development, empowerment and the transition to adulthood, I can't think of anywhere more so.

And what's the alternative? On the eve of committing to his partner, a 17-year-old scout could turn out his pockets to find a Swiss army knife, a ball of string and a tent peg, but no contraceptive – and no way of backing down if he feels uncomfortable. If we want young people to act responsibly, we're going to have to confront our squeamishness about preparing them to deal with these situations.

Robert Baden Powell, the military general who started the Scouts 101 years ago, famously advised young people with questions about sex to "take a cold shower". Such a strategy is no longer appropriate. The reality is that one-third of our young people are now sexually active before they are 16. The alternative to sex education is not no sex, but unprepared sex.

At present, our inability to talk about the differences between responsible and irresponsible sexual behaviour is leading to serious problems. The UK has one of the highest teen pregnancy rates in western Europe, and sexually transmitted diseases among young people are on the rise. Organisations like the Scouts can't be expected to bury their heads in the sand when it comes to these problems. Young people are approaching their scout leaders with questions about sex, and they need answers if they are to act responsibly.

Opponents say that engaging in these conversations encourages young people to have sex, and builds an expectation that this is something appropriate for them. But since when did learning about something encourage you to do it? We teach young physics students about the construction of nuclear bombs, but we don't expect that knowledge to drive them to blow up the science labs the next day. Similarly, Scouts might be offered training in first aid, but that doesn't mean that they're going to be more inclined to get themselves into situations where they'll have to use it. The idea that knowing more about something makes you more likely to do it is ridiculous: good sex education is about learning how to say no as much as saying yes.

If a traditional organisation established more than 100 years ago by a military general can make these changes, then maybe the Labour government could afford to be a bit more progressive and deliver on its proposals to strengthen sex education in the curriculum. After all, schools and Scouts both claim to be about preparing and empowering young people to live responsible adult lives. In the face of such a mission, failing to offer sex education isn't just irresponsible; it's also inconsistent.