SAN FRANCISCO - Sex was a hot online search topic for children in 2009, according to findings released Thursday by Internet security specialty firm Norton.

While the top three search terms for Internet users under the age of 18 were YouTube, Google, and Facebook, the words "porn" and "sex" took the next two positions, based on data from Symantec-owned Norton.

"These terms should raise a red flag to parents if they haven't had 'The Talk' with their children about content that may not be appropriate for kids," Symantec said in a release.

Boys' top 25 searches centered on social networking, games, shopping, and "adult terms," according to Norton.

Girls were also interested in online social networking websites, but their top 25 searches leaned more toward music, movies, celebrities, and television shows.

The findings were derived from 14.6 million searches conducted between February 2 and December 4 by users of a free OnlineFamily.Norton service that parents can use to filter or monitor their children's Internet use.

"When it comes to online threats, parents need to be concerned about more than just their child running into inappropriate content," said Norton Internet safety advocate Marian Merritt.

"What makes OnlineFamily.Norton unique is that it gives parents insight into kids' online activities and what interests them most so that parents can ensure they have a discussion with them about topics they're curious about, as well as protect them from cyber threats."