On the light side, the adult world has been complaining about teenagers going to the dogs since the time of the Roman emperor Augustus and this has continued unabated to the present day.
Because they live in a sort of bubble and think they know everything, teenagers can all too easily do things they later regret -- or that they would regret if anybody found out.
That's where the dark side comes in today. It's now easier than ever before to do something you might later regret -- and in the case of sexy pictures of yourself that's not "might later regret" but "will definitely regret." The pictures don't necessarily vanish into the past, not if your friends turn nasty.
Paedophiles trawl social networking sites searching for these pictures, sometimes with the intention of blackmailing the teens concerned, according to reports this week that say a quarter of teens have received 'sexts' or texts with indecent pictures.
A closer danger is that of being cyber-bullied by other teenagers. A teen texts explicit pictures of himself or herself to another teen with whom he or she is in love.
When the relationship ends, one party posts pictures of the other party on a social networking website. The pictures circulate and the person depicted in them becomes the target of upsetting and often vicious comment by others.
Teenagers also face the danger that the more sneaky type of future employer may check out their social networking pages if they make it easy for them to get access.
Why do teenagers send such pictures? It's just a version of the human tendency to show off -- the same tendency that makes poets write poetry, painters paint or adults have themselves photographed throwing back glasses of wine on holidays.
The teens are pushing it a step further and that's also a human tendency -- otherwise we would still be living in caves. But nobody is going to pay any attention to the poems, the paintings or the pictures of adults grinning maniacally at the camera.
Explicit pictures of teenagers are different -- there are people out there who want those pictures and who will gladly use them to harm the teenagers depicted, whether by bullying them or blackmailing them for sexual exploitation.
Teenagers need to remember that the picture you can take in a microsecond and -- if you're a teenager -- send in another micro-second can ultimately go far beyond the person you sent it to and can still be, at the very least, an annoyance into the future.
What do you do if you discover your teenager has been sending or receiving sexy pictures? I suggest a friendly but firm talk, pointing out the dangers of those pictures ending up on the internet and staying there for years.
Suggest that they ask for any pictures back that they may have sent to their beloved.
There's probably no need to march them off to a counsellor or down to the gardai -- it's more likely that they were being idiots than being evil.
And if you're a teenager who has sent such pictures? First, don't send any more. Ask the recipient to delete them from their phone. Second, if pictures like that are on your MySpace or Bebo page, get them off it and don't make it easy for strangers to get into your page anyway.
If somebody is hassling or blackmailing you I suggest you talk to an adult you can trust and that you consider going to the gardai -- you're not the one who will be in trouble. Don't take this on your own shoulders.
Padraig O'Morain is accredited by the Irish Association for Counselling and Psychotherapy.