Yes, these children have every right to know who their biological parents are. No one has the right to deny that information to these children. They need to know their heritage, and what illnesses they may be facing when they get older. Secrets seldom remain secrets forever. It would be best to tell them as soon as they are old enough to understand than to have them stumble across the truth.
Yes, I think that children that are conceived by sperm or egg donation should know who their parents are. I say this for a couple of reasons, but one very specific reason. If a child grows up and have children they may need to know if there are any potential issues that may occur within their child. Also it is just human nature to wonder where one comes from.
Every egg and sperm donation is carefully recorded and the centers know exactly who the biological parents are and I feel if the child legitimately wishes to know the name of who their biological parent is that they have a right to know that information, I don't feel it would be right to withhold that information.
I don't think they deserve to know who the donor is considering that the donor in question probably would've requested to not be known and donated anonymously. Also, many do it just for the money so there is no emotional attachment between the two. The child would likely just set themselves up for disappointment anyway and harm their relationship with their original parental figures.
This sort of donation is intentionally anonymous. The donor may even be doing so just for some extra cash. There is no real bond in the relationship between a donor and a user, so the bond between the child and the donor is not necessary. There is some fringe scientific evidence that such an encounter is beneficial. However, the encounters are few, and often have negative results.
I do not believe that children who are conceived by sperm and egg donation should have a right to know who their biological parents are. The knowledge that a kid possesses should be left to his parents who are legally his guardians. I think that if they decide the child should know, then it is also up to the biological parents.