A new study of American Facebook users suggests that older generations were most likely to share “fake news” stories during the 2016 presidential election.

More than 90 percent of Facebook users in the study did not share misinformation to their friends’ feeds, according to the research. Of those that did, however, the study found that age was the most significant factor. The study found that "the oldest Americans, especially those over 65, were more likely to share fake news to their Facebook friends.” This was true even when holding other factors like ideology and partisanship constant.

The researchers also found that conservatives were more likely to share fake news than liberals, but note that this may be due to an overall pro-Trump slant in fake news and not an inherent quality of conservatives.

The analysis was conducted by politics researchers at Princeton University and New York University. Their results were published on Wednesday in Science Advances, and underscore the benefits of looking at middle-age and elderly user behavior on Facebook and other platforms—especially considering the outsized influence of social media around the world.

“We were interested in a lot of questions related to learning about the political campaign via social media, but I can't say we had this particular topic in mind when we started,” Andrew Guess, the study’s lead author and an assistant professor at Princeton University, told Motherboard in an email. “But it didn't take long for us to realize what we had!”

The team defined fake news from a list of websites identified by BuzzFeed News media editor Craig Silverman in a series of investigative reports on highly-shared domains throughout the election. They further refined the list by excluding outlets that could be considered partisan, “such as Breitbart,” the study says—the authors subjectively differentiated partisanship from fake news—and wound up with 21 domains including True Pundit and Denver Guardian.

According to the study, each age cohort shared more misinformation than the preceding one, meaning younger people shared the least fake news. People ages 65 and over shared seven times as many of these stories as people ages 18 to 29, which could indicate a few things.

It’s possible that aging Americans are less able to discern if a news story is fake or credible. Digital media literacy is now a growing teaching field for both the young and old, and is crucial as older populations are becoming more active on social media.

The study theorized that, based on cognitive and social psychology, the effects of aging which may weaken “resistance to ‘illusions of truth,’” may also be partly to blame. While not mentioned by the authors, this possibility emphasizes Facebook’s own responsibility to moderate fake news on its platform before it can propagate.

The survey looked at one month of Facebook activity for 8,763 Americans. (However, only a portion of those surveyed regularly posted to Facebook.) The team asked survey respondents—with whom they connected through the polling firm YouGov—for permission to access data such as religious and political views, timeline posts, and “likes.” (Half declined to share their profile data.)

Most of the participants self-identified as white, followed in decreasing order by Black, Hispanic, and “other.”

The study also found that overall more Republicans shared fake news than democrats, but this could be due to factors that expose conservative Facebook users to more misinformation, which the study could not account for.

Guess said that sharing fake news was rare enough overall that it’s difficult to draw conclusions about which topics—Russia or climate change, for example—attracted users the most. “For this reason I'd caution against tying this into reports about ad targeting to various subgroups, etcetera,” he said.

Indeed, not all hope is lost. The study stresses how rare the sharing of fake news on Facebook was during the election, even as it points out which demographic groups partook most often.