The education minister has defended the right for Welsh faith schools to teach relationship and sex education (RSE) in line with their own beliefs.
A consultation has opened asking the public for their views on changes to how the subject is taught and its content.
Classes will begin in an 'age appropriate' way from children as young as 3 and there will be focus on healthy relationships.
Read about the proposed changed here
There will also be an emphasis on LGBT+ issues.
However ministers have no plans to change the duty for faith schools to provide relationships and sexuality education in a way that is consistent with their ethos.
The Secular Society says this gives faith schools the opportunity to distort sex education.
ITV News has read the sex and relationship policies published by some faith schools.
Staff guidelines on the website of one Catholic school said the church "does not accept homosexuality in practice" and gay sex was not morally right in principal.
There were also sections on contraception, abortion and HIV/AIDS.
The Education Minister says she wants fully inclusive relationship and sex education which meet the needs of all children and young people.
Research commissioned by the Welsh Government found a lack of research into sex and relationship education provision and quality in Welsh faith schools.
The Terrance Higgins Trust, which campaigns for awareness on sexual health, has called for clear guidelines about what happens if a school's ethos conflicts with legal equalities in areas like marriage, sexuality and gender reassignment.
There is also potential for conflicts with the rights of children and young people to impartial information with regards to sexuality and sexual health.
The Catholic Education Service said it was looking forward to working with the Welsh Government on developing the RSE provision.
"RSE in Catholic schools remains faithful to the Church’s teaching of human wholeness but recognises the contemporary context of the world we live in today. Most importantly however, it puts parents front and centre, as they are the primary educators of their children"
The intention is for the new RSE to be rolled out in Welsh classrooms from 2022.
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