The government has rejected calls from its own advisers on teenage pregnancy to make "life skills" education compulsory in England.
Ministers believe guidance for teachers is best
The Independent Advisory Group had called for personal, social and health education (PSHE) to be a statutory part of the curriculum, like citizenship.
The Department for Education has said it wants to keep the flexibility teachers have over the subject.
But it said the situation would be reviewed if necessary.
PSHE embraces other matters besides sex education and health, such as personal finance and legal and human rights.
"Teachers welcome the freedom which a non-statutory framework provides," the department said on Friday, in its response to the group's last report.
"Our current priority is to improve the effectiveness of what is taught by providing clear frameworks and guidance; supporting teachers' professional development; and identifying and disseminating good practice."
It added: "Our overall aim is to ensure that PSHE is taught as effectively as possible.
"Should the evidence show that the current process is not delivering, we shall review our approach.
"Indeed, any future review of the national curriculum would consider all the options including the case to make PSHE statutory."
The advisory group's vice-chair, Gill Frances of the National Children's Bureau, said it was disappointed by the government's stance.
"We have to ensure that the emotional and social needs of children and young people are met. The government needs to take responsibility for that through schools."
She said the main concern was to ensure consistency across the country, because teachers, psychologists and social workers were no longer trained in child development.
The advisory group had also recommended that by 2006 all secondary schools have at least one specialist PSHE teacher who held a certificate in the subject.
"Some teachers know how to do it, because that's just the way they are," Ms Frances said.
"If they are in a school where they get support from the head and other teachers, they will provide brilliant PSHE lessons."
But where schools did not make it a priority, or have the confidence or leadership to develop it, you could not rely on teachers to have the necessary understanding of children.
She stressed this was not just about sex education. The important thing was to give children a grounding in keeping safe, making friends, getting on in the world - the sort of things that concerned them.
That emotional and social development provided a framework onto which sex education could later be added, she said.
Ms Frances was pleased at the government's efforts to assure youngsters - and adults - that they could get confidential advice about personal matters.
Concerns had been raised because of the Sexual Offences Bill, which is trying to stop adults exploiting positions of trust to make inappropriate advances towards children.
The Independent Advisory Group on Teenage Pregnancy was set up four years ago to advise the government and monitor the success of its strategy to reduce the rate of teenage pregnancy - which has been falling but is still the highest in Europe.