Q. The Bible says Jesus had “brothers and sisters,” so why does the Catholic Church say He was an only child?
A. Ancient languages such as Hebrew and Greek did not always clearly distinguish among different kinds or degrees of kinship. “Brother” or “sister” was often used to designate all who were of the same family or clan. In Genesis 14:16, for example, the Hebrew text speaks of Lot as Abraham’s “brother,” though Lot is actually his nephew. In the same biblical book, Jacob calls his uncle Laban “brother” (Genesis 29:15). For this reason, some translations render the word here as “kinsman” instead.
A similar example from the New Testament involves Philip the Tetrarch. He is called King Herod’s “brother” in three of the Gospels (Matthew 14:3, Mark 6:17, Luke 3:19), yet we know from other historical sources, that he was actually Herod's half-brother, not his brother. The word “brother” is also used often in the New Testament to designate a member of the Church (see, for example, Colossians 1:2).
We read in Matthew 13:55– 56 the names of certain “brothers” of Jesus: James, Joseph, Simon, and Judas. Yet Matthew 27:56 tells us that James and Joseph were sons of a Mary other than the Virgin. Presumably their siblings Simon and Judas also were not children of the Virgin. Strictly on the basis of Scripture, we can’t say exactly what the terms “brother” or “sister” mean in this matter. For a correct understanding, we have to rely on the teaching of the Church that produced the Scriptures as a compendium of her tradition. From the beginning, the Church has always taught that the Virgin bore only one Child, our Savior.
One further consideration: If Mary had other children, why did Jesus with His dying breath entrust her into the care of someone not belonging to their family? In that culture, if she’d had other children, it would have been a deep insult, a betrayal of family loyalty, for Jesus to give her into the care of St. John. PT