My god are you ignorant. For a long time once someone reaches 18 they are considered and adult and parents have no right to view academic or medical records without permission. Also for awhile once a child hits 12-18 then in many states they have a right to privacy so parents only get access to some medical records but the child can give permission for the parents to see all the records by signing a form. If your child signs the form fine if not then there probably is a reason for them not to.
As for the questions they asked a doctor would be negligent not to ask when going in for medical care as in many cases they want to fill out a medical history and problems especially if this is a new patient to them. As for asking guns - there is also a reason because the child is more at risk to be maimed or killed when a frightened parent feels they need a gun, especially if they keep it loaded in the house.