Sermons about Jesus' mom usually center upon her private life. We break with the beaten path and focus primarily upon Mary's origin instead; which to us is a whole lots more interesting and productive than the other.
Christ's genealogy given in the gospel of Luke is sometimes appropriated to establish Mary's biological connection with David, and subsequently Adam, but we don't recommend that route because the language and grammar of Luke 3:23 is much too controversial.
Along with the language and grammar issue; there's a serious question about the listings of Shealtiel and Zerubbabel. In Matthew's genealogy, the two men are linked to David via Solomon. In Luke's genealogy, they're linked to David via Solomon's brother Nathan.
Their respective descendants are different too. Zerubbabel's son is listed as Abihud in Matthew's genealogy, whereas his son is listed as Rhesa in Luke's.
Unfortunately, to date there exists no consensus among the experts how best to resolve the confusion caused by the presence of Shealtiel and Zerubbabel in both genealogies. Were we scientific in our thinking; we'd have to consider the data compromised; and which is why we avoid using Luke's to prove that Mary was biologically related to David.
NOTE: It's been suggested that Shealtiel and Zerubbabel are common names so we shouldn't be surprised to find them listed in both genealogies. However, they are listed as father and son in both genealogies, which we cannot expect reasonable people to accept as mere coincidence.
FAQ: How was Christ biologically related to Adam without having a biological father? (Luke 1:26-34)
A: The woman wasn't a discreet creation, i.e. Eve wasn't a solo specimen constructed directly from dust like Adam was; instead, Eve was made from already-created human material taken from Adam's body. (Gen 2:21-22)
In other words: chemically, organically, and biologically; Eve was just as much the Man as Adam; except of course for gender. (Gen 2:23)
So then, any posterity that Eve's body might engender would be Adam's posterity just as much as they would be hers because every part of the posterity's bodies-- including their brains --would be constructed with material taken from their mother's body; which was, in turn, constructed with material taken from Adam's body.
Addressing the Serpent, God said:
"I will put enmity between you and the woman, and between your seed and her seed; he shall bruise your head, and you shall bruise his heel." (Gen 3:15)
Pretty much everybody on both sides of the aisle agrees that passage predicted Christ.
"her seed" indicates that Christ would be Eve's biological posterity; and if so, then he would also be Adam's biological posterity because all of Eve's bodily parts and functions were constructed of material taken from Adam's body.
It's sometimes suggested that Mary was a surrogate mother. In other words; baby Jesus was implanted in her womb as an embryo. however; her angel stated that her pregnancy would not be caused by an implant, rather, caused by conception.
• Luke 1:31 . .You will conceive in your womb, and bear a son, and you shall name him Jesus.
• Luke 2:21 . . When eight days were completed for his circumcision, he was named Jesus, the name given him by the angel before he was conceived in the womb.
In order for Mary's pregnancy to be the result of conception, her body's seed would have to be involved. Well, unless someone can prove beyond the slightest hint of sensible doubt that Mary's body was in no way the biological posterity of Eve's body, then we have to conclude that Eve's seed was the origin of Mary's seed; and if so, then the origin of Mary's seed was Adam's body.
FAQ: Can it be known for certain whether Jesus' mom was biologically related to David?
A: Yes; very easily.
First off: the angel said that David would be Jesus' ancestor.
• Luke 1:32 . . He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David.
Now, a clever sophist could construe that verse to mean Jesus was David's descendant by some other means besides biologically; however the Bible also says:
• Rom 1:1-3 . . Jesus Christ our Lord, which was made of the seed of David according to the flesh
The Greek word for "seed" in that passage is sperma (sper'-mah) which is a bit ambiguous because it can refer to spiritual progeny as well as to biological progeny; for example:
• Gal 3:29 . . If you belong to Christ, then you are Abraham's seed.
That seed is obviously spiritual progeny; whereas David's seed is biological because it's "according to the flesh" i.e. his physical human body.
Seeing as how Joseph wasn't Jesus' biological father, then we're left with Jesus' mom as the default path of Jesus' flesh to David's flesh.
● Acts 2:30 . .Therefore [David] being a prophet, and knowing that God had sworn with an oath to him, that of the fruit of his loins, according to the flesh, he would raise up Christ to sit on his throne;
Greek words for "according to the flesh, he would raise up Christ" are not in the manuscripts. The KJV's editors took the liberty to pencil them into their English translation.
However, Greek words for "fruit of his loins" are in the manuscript. Those are reinforced by the wording of the oath at 2Sam 7:12 where again David's seed is clearly implied to be physical rather than spiritual.
See also Psalm 132:11 where it's said: The Lord has sworn to David, a truth from which He will not turn back: "Of the fruit of your body I will set upon your throne."
NOTE: The Bible says: "It is clear that our Lord arose from Judah, and in regard to that tribe, etc. (Heb 7:14)
Throughout the Bible, it is normally the biological father's side of the family that determines a child's tribal identity, but in Jesus' case there was no biological father. So tribal determination defaulted to his biological mother's side.
Mary's situation was unusual but not unbiblical. Inheritance via women became an expedient back in Num 27:1-8.
Jesus' mom is sometimes alleged to be a member of Levi's tribe due to her association with Elizabeth (Luke 1:5 and Luke 1:36). However, Levi and Judah were brothers, i.e. both men were Leah's sons (Gen 29:34-35). So then Mary and Elizabeth were cousins due to their association with the same grandma rather than with the same tribe.