Amy Jenkins: There's only so much truth our online selves can allow

It seems very much a sign of the times that someone should write a blog so that people "know me better" and then admit that the blog is 70 per cent fiction.

It seems very much a sign of the times that I'm not at all surprised by this.

Nadine Dorries, the Tory MP for Mid Bedfordshire has been cleared of fiddling her second home expenses – but only because she admitted that her high-profile blog was largely a fiction. Dorries has been called the Bridget Jones MP and is known for her frank and lively online posts recounting mishaps, bad hair days and knickers dropped in the car park (dropped out of her gym bag, that is). More seriously, though, she also gives the impression in her blog that the house she rents in the town of Woburn outside Milton Keynes is her home. In fact, she lives 50 miles away in the Cotswolds.

Calling Woburn "home" in her blog but not on her expenses claims led to trouble and Dorries had to come clean with the Parliamentary Standards Commissioner to get herself off the hook. She insisted that the blog was 70 per cent fiction and 30 per cent fact and that it relied "heavily on poetic licence". She referred to it as a "tool" and said she uses it to reassure her constituents of her commitment to Mid Bedfordshire. (The reality is that, committed as she is, she's not so committed that she'd give up the more salubrious Cotswolds as her main residence.)

The reason I'm not surprised – and was even rather pleased – to hear Dorries confess what we all suspect is that we're all managing our profiles like crazy these days. It used to be only movie stars who had to manage their image, but now pretty much anyone who is online has to give some thought to it. In the internet game Second Life, you create an avatar who is "you" in the game. You get to choose your body shape, your sex, your clothes – and you walk around making relationships with other avatars while being the person that you have created. That's an extreme example, but a similar thing goes on with Facebook, Twitter or any of the social networking sites that are such a big presence in our lives these days. You may choose not to hide certain things about yourself, but you certainly work to create a positive impression.

Of course, people have always mediated themselves to some extent, even if they don't appear in the newspapers. They've done this through fashion, language, tribalism, musical affiliation and so forth. But the internet is something new altogether and it means that we all have the potential to self-publish – in the broadest sense. In fact, this must be the first time in history that ordinary people get to mediate themselves at one remove.

Now, clearly, none of this means it was OK for Nadine Dorries to be misleading her constituents – she's an MP with real responsibilities. No one forced her to write a blog and the deceptive tone of the blog was one of frankness and honesty. You might even think that the whole point of exposing one's own pratfalls would be to say: "Look, I tell it like it is", although the opposite is usually the case. Pratfalls create an illusion of honesty that better disguises manipulation.

Dorries later said that her admission of 70 per cent fiction was a slip. She meant to say 70 per cent fact. I believe her – especially given her casual relationship to self-expression. But if it was a slip, perhaps it was a Freudian one. Seventy per cent seems about right to me. If we're happy with our public appearance, there's probably a great deal of poetic licence going into it. Think of your average autobiography, your average "worked on" 60-year-old woman, your average Facebook page. Seventy per cent fiction.