It's not a black thing, it is for Christians and in the Bible.
I will list just a few, but there are so many more.
Proverbs 17:17
A friend loves at all times, and a brother is born for adversity.
Matthew 18:35 So also my heavenly Father will do to every one of you, if you do not forgive your brother from your heart.”
1 John 4:20
If anyone says, “I love God,” and hates his brother, he is a liar; for he who does not love his brother whom he has seen cannot love God whom he has not seen.
Matthew 12:50
For whoever does the will of my Father in heaven is my brother and sister and mother.”
Matthew 25:40
And the King will answer them, ‘Truly, I say to you, as you did it to one of the least of these my brothers, you did it to me.’
Romans 12:1-2
I appeal to you therefore, brothers, by the mercies of God, to present your bodies as a living sacrifice, holy and acceptable to God, which is your spiritual worship. Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect.
Why doesn’t Bush call anyone else a “brother from a different mother?”