The prime minister has rejected a call from a leading expert on public health to lower the age of consent to 15.
Faculty of Public Health president Prof John Ashton said society had to accept that about a third of all boys and girls were having sex at 14 or 15.
He said the move would make it easier for 15-year-olds to get sexual health advice from the NHS.
Downing Street said the current age of 16 was in place to protect children and there were "no plans to change it".
Official figures suggest that up to a third of teenagers have sex before the age of consent.
Prof Ashton said lowering the age by a year could "draw a line in the sand" against sex at 14 or younger.
'Recognise the facts'
He said: "We need a debate here. It's time the adults started talking about the situation to take these enormous pressures off children and young people from becoming sexually active too early.
"Also to recognise the facts of what's going on by the age of 14 or 15 so that we can respond helpfully to them and support them on this journey into adult life."
"I suspect we might be better off with it at 15 because the teachers and people who are in contact with young people would feel on a firmer footing pointing them in the right direction where they can get advice and contraception to protect their physical health from disease and other problems."
"The problem we have in this country is we still have this fantasy about young people and we live in a world of wish-fulfilment," he told BBC's Breakfast.He also said that in countries with a lower age of consent, young people got involved in sex at a later age and teenage pregnancy rates were lower.
"They are doing it and we need to be able to support them and protect them.
"The negotiation of your first adult relationship in your mid-teens some time is something that will set the record for the rest of your life.
"At the moment youngsters are getting the most incredible messages from pornography, from social media. What we are seeing is more physical abuse and mental abuse in relationships."
He said pornography was causing young people to have "strange expectations" of their relationships and this needed to be "corrected" by open discussion in a sensible environment.http://www.bbc.co.uk/news/health-24976929#story_continues_2 “Start Quote
Nick CleggDeputy Prime Minister
Do I think simply a blanket reduction in the age of consent is the answer to this difficult dilemma? No”
He also called for more resources to go into sexual and relationships education in schools.
Deputy Prime Minister Nick Clegg said he was concerned about "high levels of teenage pregnancy" but he said lowering the age of consent was not the answer.
"I'm worried, like everybody's worried, about the sexualisation of the culture and the information that so many young people are bombarded with at the moment. That's why I do want see action," he told the BBC's Andrew Marr Show.
"I'm constantly urging (Education Secretary) Michael Gove and the Department for Education to update and modernise sex education in schools which hasn't kept up with the internet age.
"But do I think simply a blanket reduction in the age of consent is the answer to this difficult dilemma? No."
The Faculty of Public Health, part of the Royal Colleges of Physicians, gives independent advice to the government.
David Tucker, head of policy at the NSPCC, said it would be prepared to engage in debate on the issue after considering Prof Ashton's arguments.
But Mr Tucker added: "Has there really been a significant change in the amount of young people having sex over the past 20 or 30 years? If it has changed, then is reducing the age of consent the most sensible way to deal with it?"
The age of consent in the UK for any kind of sexual activity is 16 for gay and straight men and women.
In England and Wales, the age of sexual consent for women has been set at 16 since 1885, when campaigners fought to raise it from 13 to prevent child prostitution.
Other countries have set the legal age for sexual consent at anything from 12 to 20.
In 2001, the age of consent for gay men in England and Wales was reduced from 18 to 16, bringing it in line with heterosexuals for the first time. Lesbians, who until then faced no statutory age of consent, were also included in that legislation.
Scotland and Northern Ireland made 16 the age of consent for gay and straight men and women later that decade.