Jesus’ brothers are mentioned in several Bible verses.
Matthew 12:46,
Luke 8:19, and
Mark 3:31 say that Jesus’ mother and brothers came to see Him. Jesus had four brothers: James, Joseph, Simon, and Judas (
Matthew 13:55). The Bible also tells us that Jesus had sisters, but they are not named or numbered (
Matthew 13:56). In
John 7:1-10, His brothers go on to the festival while Jesus stays behind. In
Acts 1:14, His brothers and mother are described as praying with the disciples.
Galatians 1:19 mentions that James was Jesus’ brother. The most natural conclusion of these passages is to interpret that Jesus had actual blood half-siblings.