Jacob had Joseph, Mary's husband, the Mary who gave birth to Jesus, the Jesus who was called Christ.
There were fourteen generations from Abraham to David, another fourteen from David to the Babylonian exile, and yet another fourteen from the Babylonian exile to Christ. The Birth of Jesus
The birth of Jesus took place like this. His mother, Mary, was engaged to be married to Joseph. Before they came to the marriage bed, Joseph discovered she was pregnant. (It was by the Holy Spirit, but he didn't know that.)
Joseph, chagrined but noble, determined to take care of things quietly so Mary would not be disgraced.
While he was trying to figure a way out, he had a dream. God's angel spoke in the dream: "Joseph, son of David, don't hesitate to get married. Mary's pregnancy is Spirit-conceived. God's Holy Spirit has made her pregnant.
She will bring a son to birth, and when she does, you, Joseph, will name him Jesus - 'God saves' - because he will save his people from their sins."
This would bring the prophet's embryonic sermon to full term:
Watch for this - a virgin will get pregnant and bear a son; They will name him Emmanuel (Hebrew for "God is with us").
Then Joseph woke up. He did exactly what God's angel commanded in the dream: He married Mary.
But he did not consummate the marriage until she had the baby. He named the baby Jesus.