E Jane Dickson: The sex lives of others are no affair of ours

I've had it with Tiger Woods. I know this will come as a severe blow to a man with the pulling power of the Large Hadron Collider, but really, I'm disappointed. I didn't much mind about the nine mistresses – I don't honestly see why anyone other than his wife and family should mind – but I wish he hadn't played the celebrity joker and checked into a sex addiction clinic.

Woods, currently in the care of Pine Grove Behavioral Health and Addiction Services in Mississippi, joins a long line of penitent priapics seeking state-of-the-art therapy for an old-fashioned trouser problem.

Michael Douglas, David Duchovny and Russell Brand have all done time in "winky-nick" (Brand's phrase) and emerged, shriven of personal responsibility for their sexual habits. It doesn't take a degree in public relations to work out that for a celebrity caught in flagrante, a stint in rehab is the quickest way to turn a love rat into a victim.

Russell Brand was at least honest about the nature of his problem. "I'm a bloke with a good job and a terrific haircut who's been given a Wonka ticket to a lovely sex factory 'cos of the fame." The same almost certainly applies to Tiger Woods. The difference is that Brand's USP is licentiousness while Woods traded on a clean-cut image. By most standards, he now looks a bit of a prat. And there is a good living to be made out of pathologising prattishness. At $60,000 a course, the Pine Grove treatment doesn't come cheap, but it's peanuts compared with the sponsorship money at stake for Woods. Thus, a shiny new cog clicks into the celebrity money-making machine.

As with every Hollywood craze, there's a knock-on effect. We are informed in countless earnest editorials that sex addiction is not just for the rich and famous; an estimated 6 per cent of adults are self-confessed "sufferers". (I imagine rather more are prepared to suffer in silence until they get caught.) And its not all orgies in suburbia, either. According to Doug Weiss, executive director of the Heart to Heart Counseling Center in Colorado, "most sex addicts are on the internet, have jobs, and most of it involves pornography and self-behaviour". Which pretty much lays the field open to any casual saddo with a computer terminal. Should you seek a more precise diagnosis, there are online sexual addiction surveys asking searching questions such as "Do you hide some of your sexual behaviour from others?".

Perhaps I am unusually naive, but I'd have thought that most of us hide quite a lot of our sexual behaviour from others. The leap from privacy to deviancy is, I think, treacherous, but it is symptomatic of a culture where the sex lives of others – be they celebrities or the bloke down the road – are routinely laid out for public consumption. I am glad my children are growing up in a culture where sex has been stripped of shame, but I'm not sure I view this avid consumption of strangers' erotic foibles as progress.

Dr Weiss is on the money when he pinpoints the internet as a factor. The universal availability of online porn has opened up the field of sexual knowledge in ways Masters and Johnson never dreamed of. Pornography has scratched an itch since the first phallus was scrawled on the cave wall, but it was a relatively specialised interest. Earlier generations (and I include my own) could, on the whole, manage their erotic lives without ever seeing strangers having sex. Now, with 250 million pages of pornography on the web, every imaginable coupling can be conjured at the click of the mouse. The traditional argument that if you don't like it, you don't have to watch it is no longer strictly applicable.

You used to have to put some footwork into procuring porn. Now it seeks you – or your children – out in your own home. I'm sure I'm not the only parent who was shaken by recent statistics suggesting that most 13-year-old boys in Britain have viewed some kind of pornography (indeed 12-17-year-olds constitute the bulk of the market) and that much of it is unsolicited; ie it arrives as pop-ups on sites attractive to teenagers.

This vicarious sexual experience cannot but affect attitudes and expectations. There may well be healthily instructive sites out there showing unenhanced people having happy sex, but I'm willing to bet there are a whole lot more involving hurt and humiliation. Among the horrifying details from this week's court case of the boys, aged 10 and 11, who sexually tortured two other children was the evidence that the accused boys were used to watching porn with their father.

There are, unarguably, real sexual pathologies which ruin lives. Equally, there are addictions requiring society's most urgent attention. Reclassifying the casual infidelities of celebrities as "sex addiction" and serving it up as infotainment helps neither case. If we want to get over our own unhealthy habits, we could start by minding our own sexual business.