Parliament is to debate whether parents should have the right to opt their children out of sex-education lessons when they become mandatory next year.
The debate is taking place later this month after a petition on the Government website was signed by more than 100,000 people in support of opt-outs from relationship and sex education (RSE) lessons.
The petition calls on the Government to protect the 'fundamental right' of parents to withdraw their children from the RSE classes when they become mandatory across secondary schools in September 2020.
Concerns are also raised about the content of the RSE lessons, which the petition says may 'cause more harm than good'.
'We have grave concerns about the physical, psychological and spiritual implications of teaching children about certain sexual and relational concepts proposed in RSE and believe that they have no place within a mandatory school curriculum,' reads the petition.
'We believe the above factors have not been given enough consideration and that many of the RSE resources being produced by lobby groups and external organisations will actually cause more harm than good, particularly when child development and psychological factors are considered.'
After reaching the required 100,000 signatures, MPs are set to debate the issues raised in the petition on February 25.
In its response, the Government clarified that although parental requests for opt-outs from sex education at the primary school level will be 'automatically granted', this will not be the case for secondary school students.
'The draft guidance advises head teachers that parents can request that their child be withdrawn from sex education as part of RSE and unless there are exceptional circumstances, they should agree the parents' request until 3 terms before the child turns 16,' it said.
'At that point, if the child wishes to receive sex education, they should be provided with it in one of those three terms. In line with the current position, there will be no right to withdraw from sex education taught in the science national curriculum.'
It also said that schools would be required to consult with parents about the content of the RSE lessons and 'take into account the religious backgrounds of their pupils'.
'Schools with a religious character can build on the core content by reflecting on the teachings of their faith. All schools must comply with the relevant provisions of the Equality Act (2010),' it added.
The Coalition for Marriage (C4M) has expressed strong opposition to the planned changes to RSE lessons, warning that they threaten to undermine the teaching of marriage, the rights of parents and the innocence of young children.
While some limited rights to opt out are provided in regards to sex education, C4M said it was concerned that these did not apply to relationships education classes, which are to be mandatory for all primary school children.
'Marriage is rarely mentioned in the guidance, despite being the "gold standard" for committed relationships,' it said.
'When it is mentioned, marriage is redefined to include same-sex marriage, and it is usually placed alongside civil partnership as if the two are equivalent. Marriage is just given as one of a number of relationship options.'
C4M added the concern that head teachers will be able to override the wishes of parents.
'It is absolutely imperative that parents retain the final say in deciding how and when children encounter complex adult relationships. As such, headteachers should not be given the power to overrule parental decisions,' it said.