> Just six days after the launch of the site, three Harvard University seniors, Cameron Winklevoss, Tyler Winklevoss, and Divya Narendra, accused Zuckerberg of intentionally misleading them into believing that he would help them build a social network called HarvardConnection.com, but instead using their idea to build a competing product.[21] The three complained to the Crimson, and the newspaper began an investigation. Zuckerberg knew about the investigation so he used TheFacebook.com to find members in the site who identified themselves as members of the Crimson. He examined a history of failed logins to see if any of the Crimson members had ever entered an incorrect password into TheFacebook.com. In the cases in which they had failed to log in, Zuckerberg tried to use them to access the Crimson members' Harvard email accounts, and he was successful in accessing two of them. In the end, three Crimson members filed a lawsuit against Zuckerberg which was later settled.[21][22]
IIRC, the idea he stole wasn't "social networking," it was "social networking for elite kids at Harvard."
https://en.wikipedia.org/wiki/History_of_Facebook#Facebook:
> Just six days after the launch of the site, three Harvard University seniors, Cameron Winklevoss, Tyler Winklevoss, and Divya Narendra, accused Zuckerberg of intentionally misleading them into believing that he would help them build a social network called HarvardConnection.com, but instead using their idea to build a competing product.[21] The three complained to the Crimson, and the newspaper began an investigation. Zuckerberg knew about the investigation so he used TheFacebook.com to find members in the site who identified themselves as members of the Crimson. He examined a history of failed logins to see if any of the Crimson members had ever entered an incorrect password into TheFacebook.com. In the cases in which they had failed to log in, Zuckerberg tried to use them to access the Crimson members' Harvard email accounts, and he was successful in accessing two of them. In the end, three Crimson members filed a lawsuit against Zuckerberg which was later settled.[21][22]