We were talking to the VP for online strategy at a big Silicon Valley company last week. Among other tasks she helps the company’s senior executives create a presence on Facebook and Twitter.

“Some of them are terrified,” she said.

What’s so scary? Many executives fear posting something personal that might prove damaging. It needn’t be a lampshade on the head, either. Perhaps it’s vacation photos from a second home that looks too opulent at a time when employees are losing jobs. Or maybe their support for a controversial ballot proposition proves a bit too vocal.

That’s why you see some executives, if they’re on Facebook at all, posed in their profile picture as if for the annual report, and with nothing personal posted to their “information” tab. Such reticence will soon be scarce as all of us recognize the powerful and important reasons for sharing our personal selves online.

What does your Facebook profile say about you? Research shows most of us have little idea. Psychology professor Sam Gosling’s book Snoop found that “people are virtually clueless about the impressions their [Facebook] profiles convey.”

Our own observation finds some folks post only professional information on their pages, while others post exclusively personal stuff. And a third group posts both.

It’s the latter group, obviously, that are the more daring: they’re crossing the nearly taboo boundary that separates the personal and the professional.

Obviously it’s never a good idea to post “personally identifiable information” that can lure identity thieves and other malefactors. And only a very careless or foolish person would publish proprietary company information onto a social media site. But what about all the stuff in the grey area–the pictures of you barbecuing at home, gin and tonic in hand? The tweet about the movie you just enjoyed? The link to that Atlantic article recommending an overhaul of the banking industry?

San Francisco Giants baseball player Brian Wilson recently came to rue tweeting about late-night partying when he had to pitch the next day. And a group of UK cops were disciplined for bragging about police car crashes on Facebook.

It’s difficult to imagine a group of company executives creating a Facebook page to celebrate the price cuts they’ve forced from suppliers or their support for a particular political candidate. Most are cautious–excessively so.

Why does it make sense to reveal our personal selves to social media sites? It may be that boundary breakers posting a mix of personal and professional information online are making a connection between what they share of themselves and their effectiveness as managers. Sharing personal information further humanizes people whose roles may otherwise make them seem remote or inaccessible. This effect extends beyond senior managers to peer relationships deeper in the organization. Seeing a more rounded person can’t help but extend and develop professional relationships, furthering the trust that’s crucial to collaborative knowledge creation–the lifeblood of innovation.

There’s a more general point here: we’re moving from a world of stocks to flows, one in which to grow and develop, collectively and individually, we need to constantly refresh our stocks of knowledge by participating in relevant flows of new knowledge. Flows require reciprocity: why would you exchange a flow of knowledge without trusting me to do the same? Yet trust is difficult to build and maintain if we keep a significant part of ourselves hidden.

Further incentive comes from seeking to improve the rate at which we find things we need but didn’t know we were looking for–a behavior we call shaping serendipity. Exposing aspects of ourselves and our interests makes it possible for others to provide advice and recommendations to us. Rather than increasing the quantity and quality of unexpected encounters, those of us who don’t disclose ourselves online may end up with more random encounters instead.

Another motive force is the extent to which our passions become our professions. People who are passionate about their work view it as a deeply personal experience, and the excitement they feel compels them to talk about it with their family and friends.

Late last year, Facebook CEO Mark Zuckerberg argued that the rate of sharing on Facebook may soon start growing exponentially. As it does, all of us will need to become more comfortable sharing ourselves online. Those who closely guard who they are, what they like, where they travel, and what they’re doing will seem out of touch and non-participative in an ever more disclosing and collaborative culture.

How much of yourself do you share online? Have you ever regretted something you’ve posted? Have you taken a risk that’s been rewarded by the response of others? Do you keep the personal and professional tightly segmented in your online persona(s)? If so, why?

The original post is here, by John Hagel III, John Seely Brown (JSB), and Lang Davison @ Harvard Business Publishing