Augustine of Hippo
Catena Aurea · Johannesevangelium 2
After this he went down to Capernaum, he, and his mother, and his brethren, and his disciples: and they continued there not many days. And the Jews’ passover was at hand, and Jesus went up to Jerusalem.
(Tr. x. in Joan. 1, 2) The Lord our God is He, high, that He might create us; low, that He might create us anew; walking among men, suffering what was human, hiding what was divine. So He hath a mother, hath brethren, hath disciples: whence He hath a mother, thence hath He brethren. Scripture frequently gives the name of brethren, not to those only who are born of the same womb, or the same father, but to those of the same generation, cousins by the father’s or mother’s side. Those who are unacquainted with this way of speaking, ask, Whence hath our Lord brothers? did Mary bring forth again? That could not be: with her commenced the dignity of the virgin state. Abraham was uncle of Lot, and Jacob was nephew to Laban the Syrian. Yet Abraham and Lot are called brethren; and likewise Jacob and Laban.