British fathers like to keep mum when it comes to discussing the facts of life.

A nationwide survey suggests that two in five fathers fail to broach the subject of sex with their offspring.

Instead, they appear to be happy to allow wives and teachers to reveal the true nature of the birds and the bees.

Fathers still seem to be in the dark

Psychologist Dr Aric Sigman

It is a situation with which most British children seem quite happy.

The Talking Puberty study, by Norwich Union healthcare, indicates many British children turn to their mothers when they want to talk about sex.

And in many cases, it is they who want to talk.

Up for discussion

Nearly half of 10 to 15 year olds actively approach their parents and bring the topic up.

In three out of five cases, they turn to their mother.

And it's not just the girls who are talking to their mothers. Twice as many adolescent boys approach their mother rather than their father when it comes to talking about sex.

But three quarters of parents assume their children find out about puberty at school.

And while that is the case for the vast majority, one in four children say they still don't know enough about puberty.

But the survey also has some positive reading for parents.

Nine in 10 children think their parents are good role models and 92% believe they explain puberty well.

Different approach

Psychologist Dr Aric Sigman said the findings highlighted differences in the way mothers and fathers approached the subject.

"The research shows there's certainly a will but not always a way to discuss sensitive topics such as sex and puberty.

"Mothers are far more proactive at seeking out a time to talk and making themselves available for questions and are generally better at reading a child's emotions.

"But fathers still seem to be in the dark.

But he added: "The average age at which children reach puberty is falling, particularly amongst girls.

Recent statistics released by the government show that in the past three years more than 400 girls under 14 conceived so it's critical that parents take an active role in educating their child about puberty and life changes."

He suggested that parents take a joint approach to sex education.