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Facebook Outs Gay Users to Advertisers

Nobody on the Internet may know whether you're a dog, but on Facebook, advertisers can tell whether you're gay.
 
Researchers at the Max Planck Institute for Software Systems in Germany figured this out by setting up six Facebook profiles, all identical, with the expectation that four of the test profiles listed themselves as straight, while the two others were for a gay man and a lesbian.
 
Simply by tweaking sexual preference, the team found that different ads showed up, even if the user hadn't made the information public. Furthermore, they found that half of the ads exclusively targeting gay men featured gender-neutral text, meaning that users wouldn't necessarily know that their sexuality was the reason the ad appeared unless they clicked on it.
 
For users who do click through, "the moment you arrive at the advertiser's website, they now know that the IP address and cookie value they have assigned to you is associated with someone that is gay, muslim, or a republican," Christopher Soghoian writes. From here, it's only a small step to associate that information with their Facebook I.D.
 
 

Read original story in Ars Technica | Thursday, Oct. 21, 2010