Young people think they are invincible when it comes to online networking sites, according to a report.The Ofcom study found more than a quarter of children aged eight to 11 routinely bypassed age restrictions to access some websites.It also revealed that many parents were unaware of the dangers their children face by posting personal details on sites such as Bebo and Facebook.Since they first appeared in the late 1990s, social networking sites have flourished with the launch of Friends Reunited in 2000 and more recently Bebo, MySpace, Facebook and a Saga site for over-50s.Ofcom said the websites - many of which are based in the US - could do more to remind people of the risks involved in putting all their details online.Robin Blake, head of media literacy at Ofcom, said: "People need to recognise that they have a responsibility to manage their own content and their children's access to content online."Normal parenting skills come into play. They need to recognise that their children are potentially at risk."When their children go out to play, parents often state ground rules about when they come back and when to meet etc."Parents need to recognise that going online has the same kind of risks. Having a computer in the child's bedroom is one of those things."But he said there were "huge benefits" for children using the social networking sites, as long as they did so carefully, adding: "We don't want parents to pull the plugs out of the wall."Bebo and Facebook state that users must be 13 or older while MySpace users must be 14.James Thickett, director of market research, said that while some eight to 11-year-olds were using the few sites specifically for children, such as Club Penguin, the "vast majority" were not.He said: "There are a number of discrepancies between what children are doing and what parents believe they are doing."Children are using the sites with far lower awareness of some of the issues that these sites entail," he said.