Here is the Haydock Bible Commentary for Matthew 1:15-16 and Luke 3:23-24
Ver. 16. The husband of Mary. The evangelist gives us rather the pedigree of St. Joseph, than that of the blessed Virgin, to conform to the custom of the Hebrews, who in their genealogies took no notice of women: but as they near akin, the pedigree of the one sheweth that of the other. (Challoner) — Joseph the husband of Mary.[3] So he is again called, ver. 19: but in ver. 18, we read, when Mary his mother was espoused to Joseph. These different expressions of being husband, and being espoused, have occasioned different interpretations. Some think that Joseph and the blessed Virgin were truly married at the time of Christ’s conception: others, that they were only then espoused, or engaged by a promise to marry afterwards. St. Jerome says, when you hear the name of husband, do not from thence imagine them to be married, but remember the custom of the Scriptures, according to which, they who are espoused only, are called husbands and wives. (Witham) — That Jesus, who is called Christ, was of the seed of David, is also evident, as St. Augustine affirms from various texts of the holy Scriptures, as in the epistle to the Romans, where St. Paul, (chap. i.) speaking of the Son of God, says, who was made to Him of the seed of David, according to the flesh. See also the promises made to David, 2 Kings vii., Psalms lxxxviii. and cxxxi. and spoken of Solomon, as a figure of Jesus Christ. (Estius)
To make some attempt at an elucidation of the present very difficult subject of inquiry, we must carry in our minds, 1. That in the Scripture language the word begat, applies to the remote, as well as the immediate, descendant of the ancestor; so that if Marcus were the son, Titus the grandson, and Caius the great-grandson of Sempronius, it might, in the language of Scripture, be said, that Sempronius begat Caius. This accounts for the omission of several descents in St. Matthew. 2. The word begat, applies not only to the natural offspring, but to the offspring assigned to the ancestor by law. 3. If a man married the daughter and only child of another, he became in the view of the Hebrew law the son of that person, and thus was a son assigned to him by law. The two last positions shew in what sense Zorobabel was the son both of Neri and Salathiel, and Joseph the son both of Jacob and of Heli, or Joachim. — “St. Matthew, in descending from Abraham to Joseph, the spouse of the blessed Virgin, speaks of a son properly so called, and by way of generation, Abraham begot Isaac, &c. But St. Luke in ascending from Jesus to God himself, speaks of a son properly or improperly so called. On this account he make use of an indeterminate expression, in saying, the son of Joseph, who was of Heli. That St. Luke does not always speak of a son properly called, and by way of generation, appears from the first and last he names; for Jesus was only the putative son of Joseph, because Joseph was the spouse of Mary, the mother of Christ; and Adam was only the son of God by creation. This being observed, we must acknowledge in the genealogy in St. Luke, two sons improperly so called, that is, two sons-in-law, instead of sons. As among the Hebrews, the women entered not into the genealogy, when a house finished by a daughter, instead of naming the daughter in the genealogy, they named the son-in-law, who had for father-in-law the father of his wife. The two sons-in-law mentioned in St. Luke are Joseph, the son-in-law of Heli, and Salathiel, the son-in-law of Neri. This remarks clears up the difficulty. Joseph, the son of Jacob, in St. Matthew, was the son-in-law of Heli, in St. Luke; and Salathiel, the son of Jechonias, in St. Matthew, was the son-in-law of Neri, in St. Luke. Mary was the daughter of Heli, Eliacim, or Joacim, or Joachim. Joseph, the son of Jacob, and Mary, the daughter of Heli, had a common origin; both descending from Zorobabel, Joseph by Abiud the eldest, and Mary by Resa, the younger brother. Joseph descended from the royal branch of David, of which Solomon was the chief; and Mary from the other branch, of which Nathan was the chief. by Salathiel, the father of Zorobabel, and son of Jechonias, Joseph and Mary descended from Solomon, the son and heir of David. And by the wife of Salathiel, the mother of Zorobabel, and daughter of Neri, of which Neri Salathiel was the son-in-law, Joseph and Mary descended from Nathan, the other son of David, so that Joseph and Mary re-united in themselves all the blood of David. St. Matthew carries up the genealogy of Jesus to Abraham; this was the promise of the Messias, made to the Jews; St. Luke carries it up to Adam, the promise of the Messias, made to all men.”
Whatever the difficulties attending the genealogies may be, it is evident that they arise from our imperfect knowledge of the laws, usages, and idiom of the Jews, from our ignorance of the true method of reconciling the seeming inconsistencies, or from some corruptions that in process of time may possibly have crept into the text. The silence of the enemies of the gospel, both heathen and Jewish, during even the first century, is itself a sufficient proof, that neither inconsistency nor corruption could be then alleged against this part of the evangelical history. If the lineal descent of Jesus from David were not indisputable, he could not possess the character essential to the Messias, nor any right to the Jewish throne. We may confidently then assert, that his regular lineal descent from David could not be disproved, since it was not even disputed at a time when alone it could have been done so successfully; and by those persons who were so deeply interested in falsifying the first Christian authorities.
