I honestly believe that as your parents, they have the parental right to check your personal account. Especialy if you have had a history of getting into trouble. But, however, impersinating you, I agree that is wrong and punishable by law. But you just have to remember, they're parents. They try their best to protect you all. But they can reach too far sometimes, because the just get scared. My mom was always tough on me, but look how I turned out, I'm not a spoiled brat.
I know my apprehensions might never be allayed. And so I close, realizing that perhaps the ending has not yet been written...
No, unless you're the kind of person who talks to 40 year old men and give them your personal information. In which case you're too naïve/immature to be on the internet in the first place.
For sites like Facebook, parents can simply friend their child and watch their stuff. If they're child refuses to friend them, the facebook is deleted.
As long as you live under your parents roof, eat the food that your parents put in front of you, that they bought with their hard earned from working multiple jobs, putting up with you for 18 years until you become a legal adult, they have every right to monitor your online activity.