I would say it's not wrong as long as when the baby grows up your honest with him/her in the long run, and let them make their own choice on what they feel about their real father :) Good luck xx
Hmm. I don't think it is emotionally wrong. And if you don't care about getting child support from the bio-dad (which would obviously come with accompanying legal hassles and obligations to let him see the child, etc.) I certainly don't think it will harm the child in any way not to have to be in the middle of all of that!
lf you go this route, I strongly suggest you get a correct medical history from the bio-dad, so you can write down the correct information on the child's chart when the pediatrician asks for family history of illnesses, allergies, etc. If this guy is the father of your other children, it probably is already information you have. But otherwise I would definitely go to the trouble to get it, even if it takes a lawyer's intervention to do so. If the sperm donor understands this is all that would be expected from him, he will probably willingly send it. (Get a record from his doctor. People have to fill out full medical histories often enough.)
Regarding how the child would feel later to find all of this out, I think he or she will feel like your present boyfriend, whose name is on the birth certificate and who was there as a dad through thick and thin, is her "real" father as the person above calls it. The child might be curious to meet the bio-dad some day, but there will be no confusion about who is dad.
Even if you decide not to tell, there might be some scenarios in which the child will need to know. Fortunately, the explanation "I accidentally got pregnant and the guy didn't want to have anything to do with any of it, and your dad stepped up," is a good one. It would carry you through, pretty much no matter what scenario caused you to need to tell.