Twenty-five years ago, my school sex education lesson went roughly thus. Puce-faced teacher to 30 inwardly hysterical girls: "Pregnancy. And now HIV. Terrible. Here's a film of a couple putting a condom on a banana. Good luck in your lives."
Alas, the complexities of young people's sex lives have proliferated wildly since then. Mostly, this is down to new technologies. The smartphone has brought us sexting, the sharing of naked pictures or videos of each other, and/or posting of them online, with or without the other party's consent.
Pornography can be easily accessed online, children can be groomed by strangers, and so on - all of which has swiftly changed the landscape.
I know. It makes me want to cry, too. But will our tears wash away the internet? No. So - onward, with this handy cut-out-and-keep-in-the-old-fashioned-hard-copy-pinned-to-the-fridge-way Modern Parents' Guide to Modern Sex Education.
Though pregnancy and sexually transmitted infections these days sound as old-fashioned as humbugs, they must still be dealt with.
What you want to say: "Don't have sex till you're 30. Then just do it once and give me a grandchild. Until then, you have no genitals. No genitals at all, do you hear me?"
What you should say: A wide-ranging, non-judgmental set of facts about contraception, childbirth, the impact STIs have on future fertility (with the occasional vivid turn of phrase such as "foetid discharge", in the hope this will act as its own form of contraception).
What you want to say: While necking gin by the pint, with tears rolling down your face: "'Come away, O human child, to the waters and the wild?/ With a faery, hand in hand, For the world's more full of weeping than you can understand'. That's Yeats's The Stolen Child, that is. But now it's the internet that wants to steal you. Don't let anyone take you by the hand. The world's more full of weeping than Yeats would have believed. Pass the bottle."
What you should say: "Darling, I'm going to need all your passwords, and please understand that I will patrol each and every one of your accounts and intervene whenever I see fit. Mummy has lived a long time and has forgotten more about perverts than you will ever know."
What you want to say: "These pictures will exist forever. They're not a teenage diary you can burn, a memory you can repress. Your earliest attempts at sex will be out there, in audiovisual form, somewhere, forever. I cannot convey to you fully the horror of this. Don't. Do. It."
What you should say: "You put anything of yourself or anybody else naked online, I will post the video of six-year-old you in full Elsa costume, crying because you've just realised you will never be a princess."
What you want to say: "If I ever find you've been looking at porn, I will clatter you. Do you understand? Now go and do some revision. But leave your phone here. And the iPad. And I'm taking the computer out of your bedroom. NOW do your revision. With a book. It's a big papery thing! Oh, never mind."
What you should say: "Darling, remember porn's not real. Try to think of the person in your bed as another human being, just like you. Possibly a little differently configured in the swimsuit areas. Whatever you've seen, he/she is unlikely to enjoy constant sex shorn of any notion of active consent, mutual enjoyment or concern for anything other than your own selfish pleasure. Keep things simple, kind and within the natural elastic limits of the body. Now, what would you like for tea?"
What you want to say: "Some people are just bad eggs. Don't try to understand them, just run. Run fast and run far. Back to me. I will always help you."
What you should say: "D'you hear me? Some people are just bad eggs. Don't try to understand them, just run. Run fast and run far. Back to me. I will always help you."
What you want to say: It's all lost in a haze of tears and exhaustion.
What you should say: "Ask someone else. I'm going for a lie-down."
This is an edited version of an article which first appeared in The Daily Telegraph, London