As Yaniv “Nev” Schulman points out, he’s got a fair amount in common with Facebook creator Mark Zuckerberg.

Both are 26, from Jewish families in New York and live enviable lives surrounded by the latest in geek-dream software. And for both, being part of what Schulman calls “the first Facebook generation” has had unimaginable consequences.

Schulman, whose parents chose his name during a spell on a kibbutz, is no computer genius. He's a photographer, who one afternoon answered an email from Abby, an eight-year-old girl who liked one of his pictures so much she painted a copy.

What transpired became Catfish, a documentary following Schulman’s friendship – largely via Facebook - with Abby and her mother Angela Wesselman, and his online romance with Abby’s 19-year-old sister Megan.

As the relationships developed over the next six months, Schulman’s filmmaker older brother Ariel “Rel” Schulman and their friend Henry Joost began recording the story. When the pieces of the puzzle stopped fitting together, the intrepid trio headed to small-town Michigan to uncover the ultimately astonishing reality behind these virtual conversations.

A hit at the 2010 Sundance Film Festival and the subject of assorted rumours about its veracity, Catfish offers bittersweet comedy and Blair Witch-like suspense while exposing the dark secrets of the Wesselman family.

Without ruining the ending, the automatic question is why a web-savvy twenty-something was so willing to open himself up to total strangers.

“I’d never done chatrooms or anything,” explains Schulman. “Of course I was always a little alert, but Abby’s first message was so sweet, I just thought I'd email back. Something about the story stirred with me.”

Everything spiraled from there. And, as he concedes, he allowed it to - it was fun having fans. “There was definitely an aspect of me wanting to believe,” he says. “It was flattering, it was interesting and [Megan] was much more fun than all the women I knew.”

His mother was rather more concerned, and at one point phoned Angela “to make sure it was all kosher.” Like her son, she was convinced.

After all, the messages weren’t from someone with a questionable username and a poorly pixilated photo, they were from a family, with a network of friends, photographs and videos online. “It was all so specific,” says Schulman.

If only he’d Googled the Wesselmans. He would now.

Clearly hurt by the experience, Schulman has become something of a crusader against exactly the kind of shmuck he was – the type who believes that what is online is sacred.

“Nobody is totally honest on the internet,” says Schulman. “When you sit down to type something you think of an interesting thing – it’s a curated version of yourself.”

And, he adds, there’s no such thing as online privacy. “Angela never expected [this story] to be shared with the world,” says Schulman. “But if you don’t want something to be public the number one thing is don't put it on the internet.

“You have these amazing free things - Gmail, YouTube, all these websites that you don't pay for. To me it’s crazy people are surprised and upset when their information gets used.

After all, he says, it’s a business like any other. And Schulman is more than aware of the opportunities to be made through social networking – his next project is an MTV reality series bringing together couples who have been dating online.

Megan, it seems, hasn’t put him off the joys of online relationships. In fact, Schulman is still a prolific social networker.

“Zuckerberg is a genius,” he enthuses. “I just don't know if he expected people to be so excited to share information with others.”