The chairmen and women of five Commons select committees have written to Education Secretary Justine Greening, urging her to make sex education a statutory subject in England's schools.
They are also calling for Personal, social, health and economic education (PSHE) to be a compulsory subject.
Currently schools are not legally required to teach these subjects, but the majority do.
Ministers says schools do not need "additional central prescription".
The Department for Education says it is "unnecessary to provide new standardised frameworks", saying teachers are "best placed to understand the needs of their pupils".
The letter, sent to Ms Greening on Wednesday, comes after the government was criticised for its response to a report by the Women and Equalities Committee on sexual harassment in schools.
The committee had called for statutory action to tackle sexual harassment in schools and for sex and relationships education (SRE) to become statutory in schools.
But the government said the legal framework dealing with such issues was "strong".
In an attempt to change the secretary of state's view, the committee chairmen and women have written to her saying: "We regret that the government's response to that report failed to seize the opportunity of announcing plans to introduce a statutory status for PSHE.
"We ask that you give serious thought to this proposal and the benefits that would arise from it.
"We also ask you to consider the consequences of failing to act; not only for the quality of education in England, but also for the lifelong consequences which can result from patchy or inadequate access to PSHE and SRE."
The letter is signed by:
- Neil Carmichael, who chairs the Education Select Committee
- Maria Miller, who chairs the Women and Equalities Committee
- Yvette Cooper, who chairs the Home Affairs Committee
- Sarah Wollaston, who chairs the Health Committee
- Iain Wright, who chairs the Business, Energy and Industrial Strategy Committee
A spokeswoman for the DfE said it was "actively looking at options" to ensure all children have access to high-quality teaching of these subjects.