There's a trove of personal information on social media sites that we are unwittingly sharing with anyone determined to track us. By using Facebook "Likes", researchers at Cambridge University were able to build astonishingly accurate and detailed profiles of people ... from their politics, to emotional stability, to their parents' marital status. Today, the sleuths on the trail of your digital footprint.

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Michal Kosinski - The Psychometrics Centre at Cambridge University

If you like that sound of thunder or more specifically, if you have "liked" Thunderstorms on Facebook, there is a good chance you have a higher than average IQ.

If you also "liked" The Colbert Report, curly fries or science, your odds go up even more. This is the result of new research from the Psychometrics Centre at Cambridge University in England. Researchers there discovered they could build a surprisingly accurate and wide-ranging profile of someone's identity, interests and habits, based purely on what they "liked" on Facebook. And if you're not on Facebook, "liking" something is just a way of publicly displaying your affection by clicking on a little thumbs-up icon.

Michal Kosinski is one of the researchers behind the new work. He was in Castelrotto, Italy.

Joel Stein on Data Mining

Your Facebook "likes" aren't the only digital sign-posts you're leaving out there on the internet. So last month, Time Magazine set-up an experiment to find out everything the internet knows about one, single person.

You can read all of Joel Stein's discoveries in his piece in Time Magazine called Data Mining: How Companies Now Know Everything About You. Below is a video with Joel Stein explaining how companies now know everything about you.

Panel: James Harkin / Vergel Evans

Accurate or not, companies such as Facebook and Google are collecting a lot of personal information from their users. James Harkin has been watching this trend closely. He is a writer for The Guardian and the Financial Times newspapers. He is also the author of Cyburbia: The Dangerous Idea That's Changing How We Live and Who We Are. James Harkin was in London, England.

And Vergel Evans is an information architect at the Ariad marketing communications agency. He was in Toronto.

No one from Facebook was available to speak to us this morning. But a spokesperson did sent us a statement. It reads ...

"The prediction of personal attributes based on publicly accessible information, such as zip codes, choice of profession, or even preferred music, has been explored in the past and is hardly surprising. No matter the vehicle for information - a bumper sticker, yard sign, logos on clothing, or other data found online- it has already been proven that it is possible for social scientists to draw conclusions about personal attributes based on these characteristics."

A Facebook spokesperson also pointed out that users can adjust the privacy settings of their Likes.

This segment was produced by The Current's Hassan Santur, Josh Bloch and Jessica deMello.

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