The question that intrigues me more is, “Why Joseph’s?” Why make it appear that Christ is not of divine origin by making it appear that he is just a biological child of Joseph’s? I believe your theory needlessly overcomplicates this out of your desire to have some kind of bloodline because for some reason you put a certain importance on it for whatever reasons.
And while it may not seem radical to you, it is a radical idea and many have tried to cast doubt on Jesus’ divinity have used the same idea to say Jesus was conceived normally and the whole ‘born of a virgin’ was a hoax. If Christ was actually genetically Joseph’s son (whether Joseph impregnated Mary or God used Joseph’s DNA before telling him about it later), there would be no way to prove Joseph didn’t sleep with her and that Jesus was a human being conceived normally by Joseph and Mary.
Why you think God would allow such a thing to occur where there would be no evidence to show Christ wasn’t conceived in a divine way, but only confirm skeptics’ beliefs he was a normal human being conceived the normal human way (despite the pleas of Mary and Joseph saying different) is beyond me. You either take the Bible account as it is, or you don’t. You are going off into conjecture and putting forth a theory that is actually harder to defend than the regular biblical account.
There is another reason why this would not be, and it has to do with the promise God made toEve in Genesis, where God told her the Redeemer of the human race will come from “The Seed of the Woman”. It’s important because for those of us who understand the fall, and the corruption of human nature, original sin and such, because of Adam’s sin, all humans are conceived in sin and are born with a sin nature. The conception of Christ took place with Mary’s DNA (the seed of the woman) and God designing and providing the other half of the DNA for the physical body of Christ (ie God, the Son of God, God in the flesh). It would have nothing to do with ANY mortal man’s DNA. It would not have anything to do with Joseph’s DNA, or any other man’s DNA. God determined all by Himself what traits His body would have, and whatever similarities Christ visually appeared to have with Joseph are coincidental. The similarities with Mary are because half of His DNA came from her.
You say “Why not Joseph?” Well my whole above response is my explanation why this would not be. God is not going to do something that is going to give more evidence to the scoffers who believe Jesus was conceived normally by Joseph and Mary. Your personal twist to this doesn’t change that fact.
There was and is no way of proving Jesus' parentage. They didn't have paternity tests then, and his physical remains are long gone.
The biblical account does not mention that Jesus looked remarkably different from the other folks around Judea at the time, so he was probably dark-haired, olive-skinned, dark-eyed. There could be, and has been, suspicion that Jesus was conceived in the normal way, by Joseph or by the milkman. If God wanted to make such speculation impossible, he could have encoded the genes to give Jesus blue skin and green hair.
The father's DNA came from the same ethnic base as Joseph's, so I ask again, why not Joseph's?