Children as young as four will be given sex and relationship education under a new bill called "Children and Social Work." Getty Images

Children starting from the age of four are to be taught about same-sex couples as part of sex and relationship education classes to be implemented in all primary and secondary schools, the British government announced this week. Under the new bill called “Children and Social Work," children would also be taught at an appropriate age about sex.

The curriculum is expected to teach students about online safety, sexting and consent. It would also focus on other issues like domestic abuse and sexual harassment. Many politicians and charities approved the new mandatory curriculum, according to the Guardian. In the past, basic sex education has only been taught in biology classes.

“The statutory guidance for sex and relationships education was introduced in 2000 and is becoming increasingly outdated,” Education Secretary Justine Greening said in a written statement Wednesday. “It fails to address risks to children that have grown in prevalence over the last 17 years, including cyberbullying, ‘sexting’ and staying safe online.”

Parents can remove their children from the classes if they so wish and schools can deliver the subjects as they see fit. But Andrea Williams, chief executive at Christian Concern, said that teaching sex to four-year-olds would be "devastating" and that it might rob them of their "innocence," according to the Telegraph.

"Children of four are should not be introduced to this. Schools need to be safe places where the innocence of children is protected," she said. "Very often sex education introduces children to concepts far too soon, destroying their innocence. This is not something that the state should be laying down. We are very concerned about this."

A survey released this week by the charity Plan International UK showed that 75 percent of British adults wanted the impact of pornography to be taught in secondary schools. Meanwhile, 71 percent wanted children to be able to discuss sexting, sending, receiving or forwarding sexually explicit messages, photographs or images via cellular phones.