Tony Blair has warned young people to take responsibility for their sexual behaviour and learn more about sex from the wealth of information on offer.
Mr Blair said young people must be in charge of their own lives
He told BBC Radio 1 - which has begun research into youth attitudes on sex - there were far more ways to discuss the topic compared to his schooldays.
The prime minister also laughed off one of the study's questions, refusing to say if he ever had a one-night stand.
He promised the survey's results would help to improve health services.
"When I was at school there wasn't any formal sex education at all," he said.
"People picked it up in all the ways, from friends, parents and so on, but I think there's a lot more information there now.
"This isn't just about formal structures, it's about networks where people are actually going to have a far better idea from talking to people what are the types of problems they may confront and how to behave responsibly, sexually."
'Up to you'
Mr Blair warned young people the government cannot "run your life for you".
"We can help with the services we provide," the prime minister said, "but the choices people make, whether in their sexual behaviour or otherwise is ultimately up to them."
Question eight of the survey asks participants if they have had a casual affair lasting only one night.
When pressed for his response, the married father of four laughed and said: "I'm afraid I'm really not getting to answering [that]."
The Bare All campaign is being run by BBC Radio 1, its sister station BBC 1Xtra, television channel MTV and contraceptives manufacturer Durex.
The results will be published in August.