Question:
Answer:
Mary is the Mother of God, the Incarnate Word, Jesus Christ. Consequently, Jesus received his DNA from the Blessed Mother, Mary and, by extension, her direct ancestors.
It is biologically correct that Mary could not have provided a Y chromosome for the conception of Jesus. Indeed, modern science affirms that women have XX chromosomes, whereas men have XY.
However, for the X and Y male chromosomes, the Holy Spirit provided them miraculously at the Incarnation, whether by genetically altering Mary’s DNA or in some other way. Which my colleague Jimmy Akin affirms via in a 2020 edition of our Catholic Answer Live show (the Q&A begins at 24:35ff.)
For more on the humanity and divinity of Jesus, please read the Catechism of the Catholic Church (CCC), 456ff.
In addition, St. Thomas Aquinas addresses the issue of Mary’s divine motherhood indirectly in the Summa Theologiae (ST):
We must therefore say that in Christ’s conception itself she did not cooperate actively, but merely supplied the matter thereof. Nevertheless, before the conception she cooperated actively in the preparation of the matter so that it should be apt for the conception (ST III, q. 32, a. 4, resp.).
In other words, while Mary provided the human matter in terms of what she could, that is, a human ovum, she still needed God’s assistance to conceive. Indeed, as St. Luke provides, Mary conceived by the Holy Spirit (Luke 1:31, 34–35). Thus, somehow the Holy Spirit supernaturally provided that which, in purely human cases, would be provided by a human father.
Further, this doesn’t mean that the Holy Spirit is the Father of Jesus. As St. Thomas adds:
And therefore we can fittingly say that Christ was conceived of the Holy Ghost in such a way that the efficiency of the Holy Ghost be referred to the body assumed, and the consubstantiality to the Person assuming (ST III, q. 32, a. 2, resp., emphasis added). . . .
Wherefore, although in His human nature He was created and justified, He ought not to be called the Son of God, either in respect of His being created or of His being justified, but only in respect of His eternal generation, by reason of which He is the Son of the Father alone. Therefore nowise should Christ be called the Son of the Holy Ghost, nor even of the whole Trinity (ST III, q. 32, a. 3, resp., emphasis added).
In summary, while the Holy Spirit was fundamental to the Incarnation, and therefore Christ’s assuming a human nature, Jesus’ divine Sonship is a matter of eternal generation, and thus his only Father is God the Father.