This has been addressed repeated on FR.
Catholic Answers:
1. The Meaning of Brother
The first thing to understand is that the term brother (Gk. adelphos) has a broader meaning than uterine brothers. It can mean a biological brother, but it can also mean an extended relative, or even a spiritual brother.
Take Genesis 13:8 for example. Here the word brother is being used to describe the relationship between Abraham and Lot, who were not biological brothers but uncle and nephew:
So Abram said to Lot, Lets not have any quarreling between you and me, or between your herdsmen and mine, for we are brothers (Gen 13:8, NIV; see also 14:12).
Because of the Bibles broad semantic range of brother, we can rest assured that although St. Paul writes, [Jesus] appeared to more than five hundred brothers at the same time (1 Cor. 15:6), we need not infer from this verse that Mary gave birth to more than 500 children!
Pretty strange to single out four "brothers" and "sisters" when the translation could mean any number of thousands of people... ?
Carry on with your traditions...
Catholic Answers:
Yup; with Catholic spin.