Schools must teach children that some families 'have two mummies or two daddies' regardless of whether they are founded on a basis of faith, the head of Ofsted has said.
Ofsted chief inspector Amanda Spielman told the BBC it was important that children know 'there are families that have two mummies or two daddies'.
She was speaking after a row broke out between parents and authorities at a school in Birmingham where children have been learning about same-sex relationships in class.
Protests against Parkfield Community School have been led by Muslim parents angry that the lessons contradict their faith. According to the Express, 98 per cent of the school population is from a Muslim background.
The 'No Outsiders' lessons were started by school assistant head Andrew Moffat, who is gay, to teach children about the Equality Act and British values.
Mrs Spielman defended the lessons, saying that they were about teaching diversity.
'It's making sure they know just enough to know that some people prefer not to get married to somebody of the opposite sex and that sometimes there are families that have two mummies and two daddies,' she said.
'It's about making sure that children who do happen to realise that they themselves may not fit a conventional pattern know that they're not bad or ill.'
She said that many faith schools were managing to fulfil their legal obligations while not promoting homosexuality.
'At the end of the day it's something that the vast majority of faith schools, even those which clearly teach that homosexuality is not right in their faith, still manage to do this in a sensitive and careful way that absolutely does fulfil the law,' she said.
The No Outsiders programme has triggered an angry response from parents who have accused the school of indoctrination.
Protestor Mariam Ahmed told the Express that: 'What they are teaching is not right, they are too young.
'There are nine parts of the [Equality] Act and they only seem to be focusing on one, homosexuality, and that is wrong. They need to have an ethos which reflects the area.
'It's not just because we are Muslims, there are Christians here too. We don't have a vendetta against homosexuals and we respect the Act.
'We respect that Mr Moffat is gay and we are happy for him to teach.'
Mrs Spielman, however, said that protests were not going to change what was being taught in school but rather 'sane, rational discussions'.
'It's proper conversations that will change it, not protests,' she said.
Last week, Parkfield's leaders met Birmingham Council representatives and faith leaders to discuss possible ways forward. The school said it would be informing parents of a decision after the half term break.