A faith-based group has urged the Department for Education to appoint an independent watchdog to monitor Relationships and Sex Education (RSE) in schools starting next term.
The Values Foundation has started a petition and by Thursday morning had almost 30,000 people in favour of the idea.
Starting in September, Relationships Education will be compulsory for all primary school students in England and RSE will be taught in all secondary schools.
Some schools in England have already started teaching the subjects, some of which the Values Foundations has concerns with.
Nigel Steele,director of the organisation, told Premier Christian News: "Obviously, many schools are teaching things well, but there are places, and more than you would imagine, where things are happening that are concerning.
"The two main issues are early sexualisation, where children have been taught things, concepts and practices they're not developmentally ready for.
"The second one is the teaching of unscientific ideas, specifically about gender identity, the idea that a child can be born in the wrong body. This is basically false and should not be happening in our schools, but it's widespread.
"And even in many Church schools, there are organisations that are training teachers in these ideas. Many of these organisations are currently affirmed and funded by the Government, which is in itself a scandal because we're talking about unscientific ideas."
The Values Foundation believes teaching this could leave children at risk of "exploitation, grooming and abuse".
As well a new independent RSE watchdog committee, the group wants schools to display RSE resources and providers on school websites and state if they promote Gender Theory - i.e. that gender is not binary. It has also called for "inappropriate RSE resources" to be blacklisted and wants assurance that RSE teaching is compatible with the science curriculum.
Meanwhile, the Council of Europe's Commissioner on Human Rights, Dunja Mijatovic, has warned that sexuality education in schools across Europe, including the UK, is under serious threat from the rise of disinformation campaigns, whose authors often claim justification on religious grounds.
She also believes that these attempts are indicative of wider efforts to suppress the rights of women and LGBT+ people.
In a blog post on the Council of Europe website, the Commissioner warns that "campaigns have multiplied across the continent, disseminating distorted or misleading information about existing sexuality education curricula."
Responding to her statement, chair of the Accord Coalition for Inclusive Education, Rev Stephen Terry, said: "The provision of sex education in Britain has long been frustrated by a lobby which, in spite of evidence showing the beneficial effects of age appropriate teaching of this topic at all key stages, has sought to frustrate or delay how and when information regarding human sexuality is presented in schools.
"The Commissioner's comments serve as an important reminder that erroneous and manipulative tactics are often employed by opponents of sexuality education. She also highlights a worrying link between these efforts and a broader opposition to the full human rights of children, LGBT+ people and women."
Listen to Premier's interview with Nigel Steele here: