Gradual sex education from a very young age would help our children not to rush into sex, to two sexual health charities told BBC Newsbeat.
More needs to be done to cut sexually transmitted infections and abortion figures among teenagers, the Family Planning Association and Brook have said.
The charities say the basic sex lessons kids get in science class aren’t adequate.
The Department for Children, Schools and Family said it was reviewing the delivery of school sex education.
At the age of 4, the names of body parts and simple ideas about different relationships could be taught to children.
The Family Planning Association and Brook feel the government isn’t giving our children enough info about relationships and sex.
He added: “All the evidence shows that if you start sex and relationships education early – before children start puberty, before they feel sexual attraction – they start having sex later,” said Brook chief executive Simon Blake, “They are much more likely to use contraception and practise safe sex.”