To protect your children, tell them:

● They can talk to you about anything, including sex, and you will support them.

● Never to post sexy selfies; preferably post no selfies, and switch off location-identification settings.

● Never to sext, particularly with people they have never met, and even with those they have.

● All about sex, and teach them the language to talk about this openly.

● What they are doing online, including chats on games and social media sites, will be monitored.

● Sites and apps inappropriate for their age are not allowed.

● To talk about sextortion with you — and you should report any incidence of this to the police.

● Being obsessed with social media will harm them. Watch out for secrecy, withdrawal, distraction and an unexplained drop in school performance.