Parents will retain the right to withdraw children from sex education, but not from relationships education. In theory, all of the parents of a school could state they do not want their children to receive sex education.
While relationships education is compulsory for primary schools, sex education is not.
The guidelines say secondary-school pupils should be aware "there are different types of committed. stable relationships" and how these might "contribute to human happiness".
Pupils should also be aware how stereotypes - particularly those based on sex, gender, race, religion, sexual orientation or disability - can cause damage.
