The New Testament Bible tells us that Jesus had a brothers named James, Joses, Judas and also other siblings including sisters who are not necessarily named.

According to the Gospel of Mark in the New Testament, Jesus had both brothers and sisters :

“…is this not the carpenter, the Son of Mary, and brother of Hames, Joses, Judas and Simon? And are not His sisters here with us?” (Mark 6:3, NKJV). 

Jesus’s siblings were, in fact, half siblings. Their biological parents were Mary and Joseph. Jesus shared the same mother, Mary. And Joseph was his adopted father. But He was conceived by the power of the Holy Spirit as revealed in the Gospel genealogies.

Click here to see Jesus’ biography seen in the New Testament Gospels of Matthew, Mark, Luke and John: http://www.jesuscentral.com/ji/life-of-jesus-ancient/biography-of-jesus-christ/jesus-Markbio.php

For more details click here: http://www.gotquestions.org/Jesus-siblings.html

 A relevant verse in the Old Testament worth noting is found in Isaiah 7, verse 14:

“Therefore the Lord Himself will give you a sign: Behold, the virgin shall conceive and bear a Son, ad shall call His name Immanuel” (Isa. 7:14, NKJV).

Jesus was born of the virgin Mary. She was His mother. God was His father. Therefore his brothers and sisters were siblings by sharing the same mother as Him.

The Bible also teaches that on a spiritual level, Jesus calls all who hear Him “brothers”. (Luke 8:21).