"There was a special man that helped you be. He gave a gift to the hospital and the doctor passed it onto me. I've always used the term 'sperm' and 'egg'." Anna
A useful way of describing a donor is 'someone who gives something to someone else to help them'. Lots of people are donors, such as blood, kidney, bone marrow, and charity donors. If possible, show ways that you donate (for example, consider sponsoring a child or take them with you while you donate blood). It's also good to refer to your donor by their first name, if known.