Forget the assertion that until the nineteenth century, people thought that heredity was purely on the paternal side. The Greek urban, homosocial leisure class thought that. But the Hebrew writers seem to have been unaware that any such fantasy even existed.
Well, of course they were. They were working farmers who spent their time with their wives and children. Accordingly, their purity and incest laws presuppose a biological relationship with both parents. I employ the present tense because those laws are still in daily use, and may be read in the best-selling book in the world.
The view that miracles are absolutely impossible is not compatible with agnosticism. Nor with science, which is purely descriptive. What if a miracle did occur?
There is an old stand-by of middlebrow, pub bore professional atheism, that the Virginal Conception has numerous mythological parallels. Nothing could be further from the case.