I think it's not just a right, but a necessity for adopted children to know about their biological parents. On an emotional level, all adopted children have a compelling need to find out about their biological parents, and they should have the right to do this. They also need to know if their biological parents were drug addicts, alcoholics, or perhaps if they had any genetic diseases.
I feel like children that have been adopted should have the choice to know about their biological parents if they choose to. It is not right for their adopted parents to not notify them and let them know about their lives and where they have been. By keeping this information from the child you are just setting up for more problems in the future.
I think they do have the right to know,but the parents should have the right to not want them to. I think if they should be allowed to see them on paper,but if the parents don't want contact, they will have to include that. A judge should rule on this before I make my statement on it.
In my opinion, adopted children should definitely know the truth about their biological parents. These sorts of children very often go through their entire lives without knowing who their true parents are. Although it can be argued that adopted parents do become the "real" parents, they should be able to have a choice in the matter. Personal choice is always better than forcing them to not know the truth.