Digital legacies can prove to be rather revealing.

Many sex workers understandably go to great lengths to ensure that their business and private lives remain separate. But a new report by Gizmodo shows that Facebook’s algorithms suggest regular clients of sex workers as potential friends, spotting links even when different details are used for professional and personal encounters. From the article:

Her “real identity”—the public one, who lives in California, uses an academic email address, and posts about politics—joined Facebook in 2011. Her sex-work identity is not on the social network at all; for it, she uses a different email address, a different phone number, and a different name. Yet ... the company had somehow discerned her real-world connection to these people—and, even more horrifyingly, her account was potentially being presented to them as a friend suggestion too, outing her regular identity to them.

The social network hasn’t explained how this kind of thing happens, as it keeps the algorithms that are used to generate those suggestions a closely guarded secret.

Some commentators suggest that the porn industry could soon face similar issues. The popular website Pornhub yesterday announced that it will start using artificial intelligence to tag people and label ... activities in photographs and videos on its servers.

While Pornhub tells Engadget that it will “only tag professional, known models rather than amateurs,” Motherboard argues that “it's easy to imagine a future in which a third party uses machine learning, facial recognition, and social media accounts to identify people in a giant database of nudes.”

Even if we don't know about Facebook's smarts, at a fundamental level all of this is being made possible by a sprawling trail of digital breadcrumbs that we leave behind online everyday. While being identified as a sex worker or amateur porn star isn’t a big concern for everyone, it could be particularly damaging for some people. Plus there’s a wider point here for the rest of us: big data may have simply made anonymity impossible for regular folks.