Facebook’s ability to figure out the “people we might know” is sometimes eerie. Many a Facebook user has been creeped out when a one-time Tinder date or an ex-boss from 10 years ago suddenly pops up as a friend recommendation. How does the big blue giant know?
While some of these incredibly accurate friend suggestions are amusing, others are alarming, such as this story from Lisa*, a psychiatrist who is an infrequent Facebook user, mostly signing in to RSVP for events. Last summer, she noticed that the social network had started recommending her patients as friends—and she had no idea why.
“I haven’t shared my email or phone contacts with Facebook,” she told me over the phone.
The next week, things got weirder.
Most of her patients are senior citizens or people with serious health or developmental issues, but she has one outlier: a 30-something snowboarder. Usually, Facebook would recommend he friend people his own age, who snowboard and jump out of planes. But Lisa told me that he had started seeing older and infirm people, such as a 70-year-old gentleman with a walker and someone with cerebral palsy.
“He laughed and said, ‘I don’t know any of these people who showed up on my list— I’m guessing they see you,’” recounted Lisa. “He showed me the list of friend recommendations, and I recognized some of my patients.”
She sat there awkwardly and silently. To let him know that his suspicion was correct would violate her duty to protect her patients’ privacy.
Another one of her female patients had a friend recommendation pop up for a fellow patient she recognized from the office’s elevator. Suddenly, she knew the other patient’s full name along with all their Facebook profile information.
“It’s a massive privacy fail,” said Lisa. “I have patients with HIV, people that have attempted suicide and women in coercive and violent relationships.”
Lisa lives in a relatively small town and was alarmed that Facebook was inadvertently outing people with health and psychiatric issues to her network. She’s a tech-savvy person, familiar with VPNs, Tor and computer security practices recommended by the Electronic Frontier Foundation–but she had no idea what was causing it.