Matt 46-50
"While Jesus was still talking to the crowd, his mother and brothers stood outside, wanting to speak to him. Someone told him, "Your mother and brothers are standing outside, wanting to speak to you."
He replied to him, "Who is my mother, and who are my brothers?" Pointing to his disciples, he said, "Here are my mother and my brothers. For whoever does the will of my Father in heaven is my brother and sister and mother."
John 7:5 also says that Jesus' bros doubted Him. John 7:5, "For even his own brothers did not believe in him." I really doubt John meant cousins, because of the emphasis on the closeness of those who didn't believe Him. John the Baptist was His cousin, of course He believed Him!
They drew the distinction and demonstrated that they could draw the distinction. The word kindred (suggenes) is translated "cousin."
Luke 14:12 And he said also to him who did call him, `When thou mayest make a dinner or a supper, be not calling thy friends, nor thy brethren, nor thy kindred, nor rich neighbours, lest they may also call thee again, and a recompense may come to thee; These lists demonstrate that words are being distinguished from one another. There is a distinction between a man's brothers and his "kindred, blood relatives, kinfolk, cousins." IN SHORT, the Protestant position MUST be admitted to be entirely tenable, and those who reject fellowship based on this difference are being dishonest with other Christians."
Lu 21:16 And ye shall be betrayed both by parents, and brethren, and kinsfolks, and friends; and some of you shall they cause to be put to death.
Mt 13:55 - Is this not the carpenter's son? Is not His mother called Mary? And His brothers James, Joses, Simon, and Judas?
Mt 12:46 - While He was still talking to the multitudes, behold, His mother and brothers stood outside, seeking to speak with Him.
Mt 12:49 - And He stretched out His hand toward His disciples and said, "Here are My mother and My brothers! This is a very interesting passage in that Jesus intentionally distinguishes between these "fellowship brothers" and the "brothers associated with Mary."
Mr 6:3 - Is this not the carpenter, the Son of Mary, and brother of James, Joses, Judas, and Simon? And are not His sisters here with us?" And they were offended at Him.