Jesus was part of an extended family. The Bible says he had brothers and sisters. Some churches try to spin that these were only cousins, or Joseph's from a previous marriage, but Mary, Jesus' mother, was not an only child. At the very least, Jesus had cousins, Aunts, and Uncles. John the Baptist was Jesus' second cousin according to Luke 1:5-38.
For the purpose of this discussion, we do not need to go into the question of whether Jesus and Mary Magdalene were married and had a family.
But the fact is that Jesus had kinfolk; blood relations, at least on his mother's side (although the Bible provides a paternal genealogy for Jesus back to the House of David).
Those kinfolk had children. Those children had children. Those children had children. And so forth.
Modern genetics testing has demonstrated that modern-day Palestinians have a direct genetic trail back to the biblical Israelites.