Found this on the subject....

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. The Bible tells us that 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. Later, in Galatians 1:19, it mentions that James was Jesus? brother. The most natural conclusion of these passages is to interpret that Jesus had actual blood siblings.

Some Roman Catholics claim that these ?brothers? were actually Jesus? cousins. However, in each instance, the specific Greek word for ?brother? is used. While the word can refer to other relatives, its normal and literal meaning is a physical brother. There was a Greek word for cousin, and it was not used. Further, if they were Jesus? cousins, why would they so often be described as being with Mary, Jesus? mother? There is nothing in the context of His mother and brothers coming to see Him that even hints that they were anyone other than His literal, blood-related half-brothers.