Please forgive me for jumping in at this point without having read the whole 3,700 posts of context. !!! And if I'm just repeating what others have said (sigh) again I ask you, forgive me.
It seems there's an unnecessary hangup here about the word "assumed."
What's confusing is that, in some contexts, "assumed" means merely to take on an appearance, even for the purpose of deceit, e.g. "he assumed an expression of indifference" "he had a disguise and an assumed name." But in a Christological context, "assume" means "to take up" or "to take upon oneself," "to adopt," or, even better, "to take as one's own."
So that when we say that the Second Person of the Trinity, the Word, "assumed" flesh or "assumed a human nature," we mean that He, the Son, a living Person from all eternity, co-eternal with the Father, took on as his own a human nature, becoming true Man, becoming what we are, including smallness, weakness, growth and development, hunger and thirst, real desires and real hurts, real pain and real death.
To use a good phrase of the Catholic Conciliar document Gaudium et Spes (para 22), "For by his incarnation the Son of God has united Himself in some fashion with every man. He worked with human hands, he thought with a human mind, acted by human choice and loved with a human heart."
You know, I was just thinking this today. The Gospels are written in Greek, but Jesus spoke Aramaic; so we have very few of his ipsissima verbi, His exact precise words as he said them. Our earliest manuscripts are, themselves, translations of His verbal preaching and teaching.
But offhand, I can think of two places where we do have the unvarnished Jesus-Aramaic: where he says "Abba" (Father) --- expressing his intimate relationship with the Father; and where He says "Eloi, Eloi lama sabachthani--- My God, My God, why has Thou forsaken me?" --- his utter abjection as a man in torment and anguish, his utter bereavement.
It's just inconceivable -- isn't it? --- inconceivable, what He did for us.
P.S. Let no one deny that Mary was Jesus' genetic mother. I mean, we don't, can't, know the details about Jesus' human genome, but we do know that Mary was His true genetic link to his human line of descent going all the way back to Adam and Eve. That is beyond debate. Jesus is absolutely, dogmatically, the son (descendant) of Adam according to the flesh.
The English word "assumed" does not find its way into any legitimate English Translation of the Scriptures in regard to the incarnation.
In the manner in which it was being used by some of our Catholic and Orthodox posters, (i.e., disputing the direct descendant genetic links between David and Christ), the word "assume" in regard to the manner in which the Word was made Flesh expresses the idea that Christ was not really a human being in the same sense as we are, that he was not genetically linked to Adam and Abraham and David, that somehow he would not have DNA like the rest of us, etc. IOW he was merely assuming a human condition, much as a criminal would use an assumed name. In that sense the use of the word "assume" would not work in a Christological sense.
Christ was Mary's child in the same way that you are your mother's child. To deny that is to deny the prophecies of his birth.