The topic might come up during a discussion of why a child is so different from her/his dad. Or someone might slip up and mention that the sperm was donated.What good does it do a child to know that out there somewhere out there is a "donor" to whom she is genetically related?
I don't know anything about sperm donation. But I don't think children whose biological father donated sperm have access to information about the donor, if it is even available. Perhaps such information should be available.