But research shows that too many parents simply try to pretend that sex does not exist when it comes to their own children.For those who do raise the subject, there is usually more embarrassment for the children than enlightenment. There does not seem to have been much advance from the toe-curling "birds and bees" talks of comedy-writers.But in fact those double standards about sex are no laughing matter. A report from the Government's Social Exclusion Unit today will reveal that Britain has the worst rate of teenage pregnancies in Europe.Modern parents may try to kid themselves that teenagers nowadays don't need to discuss these issues with their parents because of the many other sources of information at school and in the media. But they are wrong.The agony aunt pages of teenage magazines are full of heartbreaking stories that show how many young people suffer by not having the right information.

They tell of girls being coerced into sex they don't want because they think they can't say no, of teenagers becoming pregnant or infected with sexual diseases through sheer ignorance.One 17-year-old girl asked whether it were true that drinking vinegar could stop you getting pregnant. That was a playground myth when I was a child and it is truly shocking to hear that, a generation later, teenagers are still hearing - and believing - the same nonsense.The evidence shows that teenagers are more than twice as likely to get pregnant if they do not discuss sex with their parents. Our inability to talk sensibly to our kids about their bodies, sex and relationships is costing us all dear.Of course, it doesn't have to be like this. You only have to look across the North Sea to the Netherlands to realise the differences in parental attitudes to sex.

One recent study found Dutch parents are more than twice as likely to talk to their children about sex than British parents. It can be no coincidence that our rate of teenage pregnancy is six times higher than the Netherlands'.So if we really want to do something about teenage pregnancies, we as parents have to put aside our embarrassment and talk sensibly and maturely about sex to our children. During a recent visit to the United States, I saw an amazing project in the South Bronx. It trained teenagers and paid them to visit schools and youth clubs. Through drama and role play, the project workers spread the message about avoiding sex if you don't want it and using contraception if you do. They warned the pupils against being browbeaten by their peers into having sex too young.