'Brother's' in the Bible

Then the Lord said to Cain, “Where is your brother Abel?”“I don’t know,” he replied. “Am I my brother’s guardian?”

Then He said, “What have you done? Your brother’s blood cries out to Me from the ground!

So now you are cursed, alienated, from the ground that opened its mouth to receive your brother’s blood you have shed.

and stay with him for a few days until your brother’s anger subsides—

until your brother’s rage turns away from you and he forgets what you have done to him. Then I will send for you and bring you back from there. Why should I lose you both in one day?”

Then Judah said to Onan, “Sleep with your brother’s wife. Perform your duty as her brother-in-law and produce offspring for your brother.”

But Onan knew that the offspring would not be his, so whenever he slept with his brother’s wife, he released his semen on the ground so that he would not produce offspring for his brother.