If I understand correctly, your wife carried the baby made by another woman's egg fertilized by your sperm? In this case your wife only provided the nourishment of the baby..... and all the genetics (traits that you see) are from the woman who donated the egg and you, NOT your wife's genetics.

On the other hand, only if it was the pianist who carried your wife's fertilized egg (fertilized by you) the baby would carry no traits of the woman and would have only yours and your wife's genes.

Hope that makes sense.

The only thing the baby would have gotten from your wife is nourishment and a bond that can only be shared by the woman carrying the baby. It is a beautiful thing and you all are very lucky you got to experience that, your wife especially. So what if he doesn't have the same smile or hair color. She is his mother, as you are his father. It is possible that what you are seeing could resemble your wife, only because maybe the genetic mother shared qualities that resemble your wife.