Why Does Facebook Keep Suggesting You Friend Your Tinder Matches?

A year ago, shortly after breaking up with her boyfriend of three years, Emma Lauren decided to jump back into the dating scene, starting with an OkCupid account. Her first date went disastrously: the dude showed up late, looked nothing like his profile picture, spent the entire time talking about 9/11 conspiracy theories, and berated her for smoking a cigarette before he tried to kiss her at the end of the night. She didn’t speak to him again, and later blocked his phone number after he became belligerent because she didn’t reply to his texts.

After this catastrophic return to the dating world, Lauren decided she wasn’t quite ready to start seeing new people, deleted her account and moved on. She said would have never thought of the date again—except the unhinged suitor showed up in the ‘People You May Know’ section of her Facebook a few weeks ago.

The feature displays people Facebook’s algorithm has decided you might know based on “mutual friends, work and education information, networks you’re part of, contacts you’ve imported and many other factors,” according to Facebook’s Help Center page. It can be a great way to reconnect with friends from college or people from your hometown you haven’t added yet. It can also be a grim graveyard of one night stands and failed Tinder dates inserting itself into the periphery of your daily Facebook browsing.

The issue has been coming up with alarming frequency for users of Tinder and OkCupid in recent months. Others have also complained about seeing matches from gay dating apps Grindr and Jackd on their Facebook pages. I spoke with nearly a dozen women who have seen dating site matches on the list recently.

“My [People You May Know] section is mostly people from OkCupid which is very strange,” said Dani Rose, who lives in New York and uses the website to meet people. “And they aren’t people who I have saved in my phone, I might have texted them but they aren’t saved as a contact.”

“It’s always people I don’t even talk to, have deleted their number, and have no friends in common.”

Maria Ledbetter has noticed six people she has met on Tinder in her Facebook suggested friends within the last few months, including one match who showed up so late to their date that she left. She said the suggested friends from Tinder often pop up within a week of getting her number, usually in cases where she hasn’t spoken with them since.

“It’s always people I don’t even talk to, have deleted their number, and have no friends in common,” she said. “It’s really frustrating.”

Emilio Ferrara, a data science and machine learning professor at Indiana University who studies social networks said the most obvious answer would be that these apps are collecting and sharing your information.

“It is likely that these social network companies are buying data from one another, which means that Facebook can acquire some information on user activity from other platforms,” he said.”If that’s the case, it would be very easy to cross match.”

“It could also be a coincidence,” he added. “But I don’t believe very much in coincidences.”

With Facebook amassing an increasing amount of data about our lives, it’s reasonable to be suspicious of what the site knows about our dating habits, but Tinder and OkCupid both denied they share user info.

“If you choose to allow permission, Tinder accesses your Facebook friends list to establish whether you have any common connections with your potential match on Tinder,” a representative from Tinder told Motherboard by email. “Tinder is not directly involved with Facebook’s ‘suggested friends’ feature and cannot speak to information considered in Facebook’s friend recommendations.”

OKCupid similarly replied, “This isn’t something that we do.” A Facebook spokesperson told Motherboard, “We do not use information from third party apps to show you friend suggestions in People You May Know.”

Brian Hamachek, a software engineer who has reversed engineered Tinder’s API and is very familiar with Facebook’s API said there is no reason to believe those two sites are comparing your data.

“[Tinder] doesn’t even talk to Facebook again after the login, even if they did there’s no API that would suggest Tinder gives information to Facebook about suggested friends,” he said. “It seems highly suspect they’d actually be sharing that info with Facebook, and I don’t see what benefit it would serve either company.”

The answer could be in our phones—Facebook does say it bases its suggestions in part on “imported contacts,” but this is something users have to opt into on the mobile app or desktop. However, opting in may be much easier than one would think. I don’t ever remember agreeing to import my contacts, and yet when I checked my “invite history” page I had 900+ contacts saved, apparently were continuously syncing and updating, that I promptly removed. Facebook warned this could make my friend suggestions “less relevant.”

This sounds like the key, but it doesn’t explain the users I spoke with who saw contacts they never saved in their phones as suggested friends. How does Facebook know about the people you’ve chatted with only within other apps? David Liben-Nowell, a computer science professor at Carleton College who studies the structure and evolution of social networks, said it could also be that people who have searched your name before––not an unreasonable precaution before meeting someone from the internet for a date.

“My hunch is that [Facebook is] using names you’ve searched for or profiles you’ve viewed to suggest friends to you,” he said by email. “It would almost be silly for them not to: if you’ve shown an interest in a person while using Facebook, then you’ve as good as told Facebook that you might want to have some kind of relationship with them (whether that’s an OKCupid-style relationship or a Facebook-style friending).”

Liben-Nowell said it isn’t clear if Facebook suggests friends based on people who have searched for you as well, but it would make sense to include that search trail in its friend-finding algorithm. He also noted it could also be a chance internet encounter that particularly sticks out if it’s someone you had a bad experience with.

“I’m sure that some of what’s going on is a purely psychological effect,” he said. “You’d probably never remember any of the total strangers whose pictures pop up as suggested friends. But when a familiar face shows up, even if it happens pretty rarely, you notice it and remember it. And if it’s the face of a Tinder match, you’d freak out a bit too—even if it was just a coincidence.”

Lauren said she certainly sees, or perhaps just notices, the people who she’s had a bad date with on Facebook’s suggested friends more often than people she got along with.

“For me it’s kind of funny, but I could see how that could be a potentially scary situation for someone, depending on the person,” she said. “It always seems to be the ones something went horribly wrong with you see, not anyone you had a nice time with but things didn’t click.”

“It could also be a coincidence. But I don’t believe very much in coincidences.”

Hamacheck said the Tinder and Facebook overlap is most likely a side effect of similar algorithms working to connect people.

“Tinder kind of operates in the exact same way Facebook suggested friends does: it looks at your current friends and suggests other people that are in that same circle of friends you aren’t friends with yet,” he said. “They’re trying to do the same thing so it makes sense they would come up with the same results or overlap.”

With the increasingly murky ecosystem of social connections these apps are creating for us, it’s hard to say exactly how we “might know” these people to begin with. Anyone who has used more than one dating app can tell you how often they find themselves swiping left or right on the same people, potential matches who are apparently within our social or geographical range but have not yet crossed our paths. So whether it’s purely coincidence or Facebook’s increasingly predictive and invasive algorithms, just as we used to run into ex lovers or dates gone wrong at a bar or the grocery store, we’re now bumping into “people we may know” more often on the internet.