The children have the right to know who gave birth to him/her. They could use their parents to ask the questions they have always been wondering about themselves and their questions would be answered truthfully. I feel like when they get old enough, they should get to know the truth about their birth parents.
People who have been adopted will sometimes wonder about where they come from. When they reach a certain age, they should have access to this information if they want it. This would help not only answer questions for the adopted person, but could be potentially life-saving when it comes to family health information being accessible to doctors.
Think about it. That's the whole point of being adopted! I mean, you got adopted for a reason. I feel that it wouldn't make any sense to tell your child' "you're adopted, your real birth parents are.." I don't really think its necessary to tell them, if they've lived a healthy, fine, and normal life. However, if they ever start to question "Why don't I look anything like you guys?" Or, "We are total opposites!" And they know what adoption is, tell them for their sake. But if they're living a perfectly normal life, what's the need?
When an adoption takes place, it can be open or closed. In an open adoption, the child certainly has the legal right to find out more about his or her parents. In a completely closed adoption, though, the child may be kept from knowing more about his or her birth parents. This can be difficult for the child, especially with not having a known family medical history. That being said, it's important to respect the wishes of the parents who originally gave the child up for adoption. This shouldn't keep the child from taking steps to find a parent if they want to through other means (like websites), but if the parents are still unwilling to be in contact, then they need to respect that.