Lisa Markwell: How much snooping on our children should we do?

How many parents will have surreptitiously looked at their daughters' Facebook pages this week? Or waited until they have gone to sleep and then scrolled through their text messages? As details of the connection between and movements of 15-year-old Megan Stammers and 30-year-old teacher Jeremy Forrest emerge, fear and panic emerge too, for all mothers and fathers of teenage girls.

They discover that BlackBerry Messenger correspondence (a preferred method of communication for many youngsters) is easily deleted; and that their Facebook account, the one that accepted you as a 'friend' when your child was younger, is dormant – they share their pictures and innermost thoughts under another name. You are not a friend of that person; you don't know who they are.

The problem is that all of this is perfectly healthy, most of the time. It is important for young people to develop their own personalities and relationships without mum and dad breathing down their necks. The general rule is that no good can come of prying into your child's social media activity - like eavesdropping on phone conversations of old, it's difficult to get the whole picture and it's easy to get hold of the wrong end of the stick.

Searching for the kind of information that parents think they want to know only shows them what they don't need to know. Yes, they look at porn; yes, they get pissed and take photos of each other in front of beer-can mountains; yes, they get crushes on people and do whatever is the digital equivalent of practising their married signature. It may make parents shudder, but it is very unlikely to reveal a teen's state of mind, or their secrets. Our digital age allows them to hide that from adults; that genie is out of the bottle. We must accept that.

(The exception to the rule is Twitter, strangely, where Stammers and Forrest exchanged comments: this public forum for declarations and opinions is latterly being adopted by young adults for whom bragging is irresistible.)

And yet… It would an utter dereliction of duty for a parent to ignore their teenager's vulnerabilities. They must be vigilant; the search for signs of obsession, withdrawal or danger must be in place. But it will have to be in person. Adults are as guilty of spending time on our laptops and iPhones as children. We must put them down to look, and listen, when a child is around. I believe, truly, that the signs are often there if we can only slow down to tune our antenna in the right direction.