Could be or the Christmas decor could be props for a "look what's under the tree that needs opening" layout of a porn mag.
If Gilbert went to the house and did measurements, then I believe him that it's Davis' house. However, I don't know if that's SADO and I don't know who the daddy is. I do know Hussein's an evil liar out to destroy America.
The odds of it being anyone other than SADO are very long in my opinion. What is the likelihood of two women who are identical in appearance, knowing Frank Davis around about 1960, and have a crooked tooth in the exact same spot?
Now as far as him being the father, just because he photographed her naked does not necessarily mean that he is the father. If the photos were taken in 1960, then it certainly makes it more likely, because this was just about the time she became pregnant.
If the photos were taken from 1962 to 1965, (also a possibility) then obviously they have no bearing on his paternity or lack thereof. I am assuming they were taken in 1960 based on the lack of discernible stretch marks or other evidence of child birth. This is, of course, not conclusive, because some women can give birth and not long thereafter show no visible signs of having done it, though many women do show signs of child birth.
But you are right, we don't have conclusive evidence of who the father is. I won't be surprised if it's either of them, or neither of them, though at the moment I am leaning towards Frank.