My sister has some questions about Jesus, his bloodline and any possible siblings?

He never existed, and according to the Bible, his bloodline is cursed. That's because the New Testament totally conflicts with the Old Testament. In other words, Christianity is anti-biblical, and therefore anti-christ. The Bible should be allegorically interpreted because it contains many spiritual truths that will lead us to God, who is a spirit. Not a man. We all sin. We all try not to. There is no hell in the bible. That's a false doctrine by the Church.