I've known sense I can remember. My parents were up front with me. After my first daughter was born, I wanted to find out about my medical history and told my parents about my attempts to find out about my biological donors. (I say that because my parents raised me, not my bios) They were so touched that I don't think of my bios as parents, but just the starting point of my life that they even helped me find what I could. It has brought my relationship with my parents even closer because they picked me, not some other baby boy, but ME. Approach them that way and all should be well