Re: Can they still check what I've been on?
It depends how much techy is your dad or your relatives are.
It is possible but for that one must have good information how to recover files.
It is also possible if someone has installed a keylogger on the pc to log keys of other users.
System Restore thing is a utility to bring back the system Settings and system files state back to a date when a backup was made. It doesnt effect much on the files you have saved in your pc.