I have to side with NOP. As the “father” of an adopted child of unknown parentage, I can attest that there are issues. You may say that there are no health issues, but there are. For the rest of the child’s life doctors will ask about family health issues. Does heart disease run in your family? Is there any diabetes on either side of your family? Has any close relative been diagnosed with various types of cancer? If you don’t know the real father (or in my case either parent), you simply can’t answer those questions. Life goes on without those answers, but if they weren’t important, doctors wouldn’t keep asking.
You should also consider the child years from now. If you were to find out now that your father wasn’t really your father, how would you feel? Deceived? Lied to? I would. It wouldn’t change the feelings I have for the father who raised me, but I would wonder why I was never told the truth.
Just one man’s opinion and worth every penny you paid for it.