Last week, I learned a valuable lesson: never, ever leave young kids on their own with a computer -- even if they are only logged into www.bobthe-builder.com.

We were at home after school and I was telling them about my favourite programme as a kid: Sesame Street. I have tried in vain to obtain DVDs of the old Sesame Street programmes -- but no luck -- and any on sale on Amazon or eBay seem to be fitted for US DVD players only.

So I decided to look some up on YouTube so that the little angels could enjoy the good, clean, educational fun that is the wonderful Children's Television Workshop.

There we were, a happy little family group laughing at the antics of Oscar the Grouch, Big Bird and Kermit. My phone rang and I directed my seven-year-old to click the next clip -- one involving Bert and Ernie, the four-year-old's favourites.

"Mammy, I don't understand what they are saying," she shouts.

The four- year-old is chanting something that sounds suspiciously like: "Big d**k, big d**k, big d**k."

Mother of God, what on earth have they logged on to?

I check, and it's the same YouTube Sesame Street site but some joker has inserted x-rated clips about the sexual preferences of Bert and Ernie.

The following day I relate the story to some other mothers, most of whom have young teenage children. And, oh, how they laughed. "How quaint, how sweet, how innocent. Baby, you ain't seen nothin' yet," was how the conversation unfolded.

I was regaled with stories that made me wonder if the only way I could protect my family from violent pornography would be to move to an Amish community.

Example: one professional middle-class mother described her shock at finding a short video clip that had been downloaded from Bebo on the history file of her computer.

"I watched it because I knew that my 12-year-old son had obviously been sent it by friends. It was a recording of a very young teenage girl --unconscious, or very nearly -- being repeatedly raped, in every way imaginable, by a group of teenage boys.

"What shocked me most was that this wasn't some video of porn actors paid to perform a gang rape -- this was the real thing."

Soft porn, violent porn, perverted porn; every kind of sexual depravity you can think of -- and many you cannot -- has been documented as existing since time immemorial. Whatever your fetish, there's always someone who has beaten you to it.

Teenage boys have always swapped dirty postcards, "read" porn magazines, and watched impossibly gorgeous Swedish porn stars doing all kinds of everything to each other on pay TV.

So, am I over-reacting when I say that I am truly scared at the fall-out from the current popularity of "reality sex" videos and the way that they have become normalised within the teenage social networking culture?

I don't think so. But if you are a parent of a teenage boy or girl and you disagree with me, try this experiment.

Log on to the computer that he or she uses. Look up the history file. If it has been deleted, worry.

Ask them for their Bebo/ Facebook password. If their mates can access their page, why can't you? What's that? They are entitled to their privacy? Not if they are under 18, under your roof and you're paying for their internet access, they're not.

Check the video and film images on their mobile phones. Yes, I know your little Jimmy/Chloe/Oisin wouldn't dream of downloading nasty video clips, but that doesn't mean they don't receive them from their less wholesome friends.

What should you be looking out for? Well, here's an example of real-life teenage sex videos that have made it into the news recently.

Earlier this month in London, a video clip spread like wildfire on YouTube. It showed a 25-year-old mother who had been drugged by a "trusted neighbour" being raped by three boys between the ages of 14 and 16. In the background you can hear the cries of her two-and four-year-old children. And 600 people watched this clip on YouTube before someone had the decency to report it.

Last November, eight Australian boys drugged and sexually assaulted a 17-year-old girl. They filmed the adventure and distributed it via mobile phone with the heading: C**t the Movie.

In January, a 16-year-old English boy admitted making indecent images of a child after using his mobile to film his friend having sex with a 14-year-old girl and sending it to her classmates. Boys get their mates to video them having sex with paralytically drunk girls in nightclub toilets.

The mothers I've spoken to are -- to put it mildly -- terrified of the potential consequences of their kids either taking part in, or being sent, these "reality sex" mails. And also wonder to whom they can report it -- anonymously -- if they find explicit material on a family computer.

"Parental control software can be of little use", says one. "My kids know how to turn it off, and even with a new code so much stuff gets through the loop."

Another mother of a teenage boy said that when she confronted him after finding a recorded video of a teenage girl having sex with six men, which he said had been sent to all his friends on their Bebo sites, he just smirked and said: what could he do, he gets this sort of stuff all the time.

"I hope you know it's not real," said his distraught mother. "Don't think that girls who aren't getting paid do this for fun."

"But it is real," he said. "And they are doing it for fun."

In the way that reality show "celebrities" have replaced proper actors in the entertainment chain, kids with mobile phones are the new "porn stars".

Another mother said that her son and his peers seemed to be proud of the fact that they download and watch violent reality porn.

"There's a new acceptance of sexual perversion," she said. "Teenagers' perception of what qualifies as rape or assault has changed."

And it's not just teenagers. As Emer O'Kelly reported in this newspaper two weeks ago, seemingly we also have teachers -- moral guardians of our youth, for Christ's sake -- who don't see any reason to report (or punish) the kids who bound, gagged and assaulted a 15-year-old girl and then sent the video around to their classmates. And just in case we thought it was a once-off event perpetrated by a few obnoxious lads, journalist Niamh Horan added, "As appalling as this recent case was, this type of thing is part and parcel of school antics. It's unfortunate. But it is."

The minute I read that, I started looking up all-female convent schools for the seven-year-old to attend -- and boot camp for the boy.

This is the tip of the ice-berg. Every weekend teenage girls are getting trashed at their local nightclub and then videoing themselves feeling each other up for the lads' enjoyment. I have no idea why they devalue themselves so much that they do this for peer acceptance, but they do. Of course, they wouldn't call it that -- they call it being "sexually emancipated", God love them.

Ellen O'Malley-Dunlop, Chief Executive of the Dublin Rape Crisis Centre, gave me some idea why young girls may be so accepting of what most adults would consider to be serious sexual abuse. I chatted to her about my fears for young girls (and boys) who are becoming increasingly desensitised to violent, degrading, sex acts.

"We are very concerned about the link between the increase in sexual violence and the rise in popularity of hard-core pornography. All women involved in pornography are victims. They are usually from lower socio-economic backgrounds and have little choice," she says.

But what about the new trend in 'reality sex videos' among teenagers?

Why are young people indulging in degrading, vengeful sex-acts and thinking that it's normal?

O'Malley-Dunlop believes that the objectification of the female body and the use of sex to sell everything from computers to cars has desensitised many young people to the reality of what they are watching/doing.

Add to that the spread of hard-core pornography via the internet and mobile phone, and there really is no escaping the conclusion that violent pornography has become normalised within teen culture.

"Women are increasingly dehumanised in popular culture and portrayed as purely sexual objects. Remember those 'porn star' T-shirts for small girls?" she asked.

(I do. Other varieties included 'I f**k like a porn star' and 'I'm not a porn star but ... ')

I tell her of being appalled at seeing Playboy pencil cases and other accessories being marketed to girls as young as three.

"When sex is marketed as a commodity to children, what hope do they have of experiencing healthy intimate relationships in later years?" she says.

"Pornography is now mainstream and it is extremely addictive. And, believe me, when people are exposed to it for a long period of time they can feel as if their souls have been taken from them".

What will happen to our young people, reared on a diet of pornography masquerading as mainstream sex?

"They will get to age 30 and feel bereft, having had every sexual experience imaginable, but they will know nothing about intimacy," she says.

And how sad is that?

Rape Crisis Centre Freephone: 1800 778888

- Carol Hunt