If you suspect your teen is up to some sneaky stuff on the Internet, you're probably right.

A new study by online security software maker McAfee found that 70 percent of teens hide their online behavior from their parents.

Probably not surprisingly...

42-percent of the teens surveyed checked out violent content online and just under a third surfed for porn.

Perhaps more surprisingly...

About one in ten teens hacked into social networks or email accounts.

And about the same number had a face to face meeting with someone they met online.

McAfee says clearing the browser history is the number one way teens hide their online behavior from adults.