did you read my post? It was not Mary's egg otherwise Jesus would not have been perfect.
He would also not have been human.
The whole point of Jesus being born of a woman was that he needed to be a human being. Granted, God could have put an already fertilized egg into Mary's womb, but why would he do that? Why not just create a full-grown man called "Jesus" instead of having him grow in a womb like any other human? That's what he did when he created Adam, right? A full-grown man right out of the gate. Jesus is supposedly the "second Adam", so it would make more sense that way.
I don’t understand the logic of Christians thinking that, for some reason, Jesus needed to be perfect. This is simply not true. He needed to be sinless, not perfect. If fact, he needed to be imperfect, in the sense that he needed to be subject to the same temptations and ability to sin as anybody else. Had Jesus not have received this vulnerability from Mary, he would not have had it at all. He would have been 100% divine and therefore impervious to temptation and incapable of sinning. And if that were the case, then he would not have qualified to be the ultimate sacrifice for sin.
Hebrews 2:17 - He had to be made like His brethren in all things, so that He might become a merciful and faithful high priest
Hebrews 4:15 - “For we do not have a high priest who cannot sympathize with our weaknesses, but One who has been tempted in all things as we are, yet without sin.”
In order for him to become a “faithful high priest”, he needed to be subject to the same weaknesses as any other human being. If he was “perfect” during his lifetime, that could not have happened. He would not genuinely be able to sympathize with our weakness. This “Jesus was perfect” stuff is just bad theology, and people who believe that don't seem to realize that it shoots a hole in the very "substitutionary sacrifice" doctrine that they love so much.
Regarding the question of whether Jesus, if born of Mary, would have inherited a “sin nature” from her, I think the mistake here is that in making this assumption we are actually superimposing Pauline theology onto the writers of Matthew and Luke. We are assuming that they knew of this “inherited sin nature”. But in fact this was a purely Pauline invention. There is no hint in either Matthew or Luke that those writers had ever heard of such a thing. So, that being the case, when they wrote their virgin birth stories, they would not have considered it a problem. They wanted to make Jesus a demigod – have divine and half human. The thought of Jesus’ human half somehow inheriting a “sin nature” from Mary would have never entered their minds. This is one of many areas where Paul and the gospel writers clash. Evangelicals need to get it through their heads that the various Bible writers do NOT speak with one unified voice and they did NOT all believe alike.
