“Impossible,” we hear you gasp, guiltily minimising your other, smuttier browser. But according to Bill Tancer, general manager of global research at Hitwise, it’s true. Adult Entertainment categories have fallen behind social networking sites for 18- to 24-year-olds.

In his ‘Science Of Search’ column, Tancer examines Hitwise data to find out where Gen Y is spending its browsing time. It turns out the Adult Entertainment sector has been in decline over the last two years, with visits to porn sites dropping from 16.9% of all site visits in the US in October 2005 to 11.9% as of last week. That’s a 33% decline. So what’s taken the attention away from T&A? Well, for 18- to 24-year-olds, it’s – you guessed it – the equally voyeuristic pleasures of social networking!

Social networks like the ubiquitous Facebook rank first, followed by search engines, then web-based mail, leaving poor ol’ porn languishing half-cocked in fourth place. Interestingly, though, for web users over the age of 25, Adult Entertainment still comes in second most popular after search engines. Nice to know there’s something to look forward to when your Facebook friends prove fair-weather…

According to the data, the trend is set to continue, with social networking on the rise and virtual sleaze on a steady spiral to purgatory (or close enough). So what does this all add up to? Well, as Tancer himself muses, perhaps 18- to 25-year-olds are just “too busy chatting with friends to look at online skin.” Your parents would be ashamed.

Surprised by these findings? Head to the inthemix forums and tell us what you really think!