The interpretation timeline
Luke 8:20 Douay-Rheims

And it was told him: Thy mother and thy brethren stand without, desiring to see thee.

A.D. 378 – 1849 5 witnesses

Patristic

before A.D. 750
378
A.D.
Titus of Bostra Patristic
d. c. A.D. 378
“His brethren thought that when He heard of their presence He would send away the people, from respect to His mother’s name, and from His affection towards her, as it follows, And it was told him, Thy mother and thy brethren stand without.”
397
A.D.
Ambrose of Milan Patristic
A.D. 339–397
“In a mystical sense he ought not to stand without, who was seeking Christ. Hence also that saying, Come unto him, and be enlightened (Ps. 34:6. Vulg.). For if they stand without, not even parents themselves are acknowledged; and perhaps for our example they are not. How are we acknowledged by Him if we stand without? That meaning also is not unreasonable, because by the figure of parents He points to the Jews of whom Christ was born, (Rom. 9:5.) and thought the Church to be preferred to the synagogue.”
Source
735
A.D.
Bede the Venerable Patristic
c. A.D. 672–735
“For they cannot enter within when He is teaching whose words they refuse to understand spiritually. But the multitude went before and entered into the house, because when the Jews rejected Christ the Gentiles flocked to Him. But those who stand without, wishing to see Christ, are they, who not seeking a spiritual sense in the law, have placed themselves without to guard the letter of it, and as it were rather compel Christ to go out, to teach them earthly things, than consent to enter in themselves to learn spiritual things.”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“And he answered and said unto them,.... Not to his mother and brethren, but to those that told him of them, who either designed to reproach him with them, by reason of the meanness of them, or to interrupt him in his work: my mother and my brethren are these; pointing to his disciples: which hear the word of God; which he had been preaching, and was meant by the seed in the preceding parable: and do it; behave in their lives and conversations agreeably to it; and observe the precepts and ordinances in it; elsewhere called the will of God his Father; See Gill on Mat 12:49. See Gill on Mat 12:50.”
Source
1849
A.D.
1774–1849
“These brethren were not the sons of the blessed Virgin Mary, mother of God, as Helvidius wickedly taught; nor yet the sons of Joseph, by another wife; for, as St. Jerome writeth, not only Mary, but Joseph also, observed virginity. (Contra Helvidium, chap. ix. et ibidem, chap. viii.) — In the scriptural idiom, cousins are called brethren. (Bristow)”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.