genealogy of Christ
The New Testament has preserved two different genealogies of Our Lord, in Matthew 1; and Luke 3.
Saint Matthew's list is divided artificially into three equal parts of 14 names each, with several intentional omissions: from Abraham the father of the chosen people to David the king, to whose family the promise was made (2 Kings 7); David and the royal line after him to the Babylonian captivity; the descendants of the royal line from the captivity to Joseph, the legal father of Our Lord.
Saint Luke proceeds in reverse order; he starts from Joseph and goes, beyond Abraham, back to Adam the father of the human race, in accord with the character of his Gospel; and he merely enumerates the names without grouping them according to a thesis or point, as is the case in Saint Matthew.
Few names are common to both lists: viz., those between Abraham and David, then Salathiel and Zorobabel after the captivity, and Joseph the foster-father of Christ; the others are absent from Matthew's list, or the persons are different.
To account for these differences several explanations have been advanced, but no decisive evidence is extant.
Not a few authors hold that Saint Luke gives Mary's genealogy; but this view is more generally considered improbable, so that both lists are taken as giving Joseph's ancestry.
Only it must be supposed that at several points, instead of the actual descent, the one or the other of the lists gives the legal relationship based on adoption in some manner.
Our Lord was considered to belong to the family of David; this seems to be taken for granted in the New Testament, where we find no difficulty raised against Him on the ground of His descent.
The genealogies show His relationship to the royal family of Juda through Joseph, as it was only through the father, legal or natural, that the rights could be transmitted, and Joseph was the legal father of Jesus.
To trace Our Lord's ancestry through His mother would not have served the purpose of the Evangelists.
New Catholic Dictionary