it is important to note that the Bible does notsay that these "brothers and sisters" of Jesus were children of Mary.
Second, the word for brother (or sister), adelphos (adelpha) in
Greek, denotes a brother or
sister, or near kinsman. Aramaic and other Semitic languages could not distinguish between a blood brother
or sister and a cousin, for
example. Hence, John the Baptist, a cousin of Jesus (the son of Elizabeth, cousin of Mary) would be called "a
brother (adelphos) of Jesus." In the plural, the word means a community based on
identity of origin or life.