The theory about Jesus having a family and a bloodline that is still alive today was popularized by Dan Brown in his novel "The Davinci Code", which was adapted into a movie starring Tom Hanks. However, many authors have dismissed Brown's story as a work of fiction. While many theorists support Brown's claim that Jesus's bloodline lives on today, they dispute the assumption that their is a singular, supreme descendant (the film depicts a singular descendant in the character of Sophie Neveu). According to theorists, Jesus's descendants encompass a very wide net of people.
Even the Bible makes mention of Jesus's blood relatives. In addition to Jesus's mother, the Virgin Mary, there was Mary's cousin Elizabeth and her son who would grow up to be John the Baptist. The Bible also documents Christ's siblings: some unamed sisters and four brothers, Judas, Simon, Joses, and James. However, records from Jewish families tell the stories of other family members who were not recorded in the Bible. These records mention uncles, cousins, nephews, and even grand-nephews and great-grand-nephews. Records show these relatives being traced back to Jerusalem, Jordan, and even to Rome. These records also indicate that these relatives helped lead Christ to safety after Jerusalem fell in 70 AD. They also testified before Roman emperors. There is also the matter of the first Christian bishops. For the first 100 years after the death of Christ, the bishops in Jerusalem were not only Jewish but they were also all related to Christ.
The gospels that have been unearthed hinting at Christ's family over the years were rejected by the early Christians to be included in the New Testament. Modern Christian scholars claim that the reason why these gospels were rejected was because the early Christians considered them to be heretical. While heresy is a matter of opinion, it is also important to realize that these gospels revealed a very different picture of Christ and his mission on Earth.