More than one in five American adults copped to secretly accessing the Facebook accounts of their friends, spouses or family members in a recent study.

In a survey of 1,308 U.S. adult Facebook users, University of British Columbia researchers found that 24% – or more than one in five – had snooped on the Facebook accounts of their friends, romantic partners or family members, using the victims’ own computers or cellphones.

“It’s clearly a widespread practice. Facebook private messages, pictures or videos are easy targets when the account owner is already logged on and has left their computer or mobile open for viewing,” said study author Wali Ahmed Usmani.

People admitted to spying mostly due to curiosity or fun. Many said they had set a victim’s status or profile picture to something humorous.

On the other hand, some people said they were motivated by jealousy or animosity.

“Jealous snoops generally plan their action and focus on personal messages, accessing the account for 15 minutes or longer,” said computer science professor Ivan Beschastnikh. “And the consequences are significant: in many cases, snooping effectively ended the relationship.”

According to the authors, their findings show how ineffective passwords and device PINs in stopping unauthorized access by insiders.