Discussing the true meaning of spirituality is difficult for many have false perceptions of reality and become upset when the truth is clearly spoken.
The Sadducees question on resurrection was really a question on the family of a messenger (nine is the mandala number) and your eternal soul mate. The Sadducees ask Jesus if a family having seven sons and no son has a child from the same woman as was customary when a brother had no children and died.
The Sadducees ask who will be the the woman's husband in Heaven?.
Jesus answers that people "are like angels in heaven" and that God is of the living not the dead.
The transmission of enlightenment does not have to be within a family. The House of David ended with Jesus as Jesus had no known offsprings. Leaders of religious orders can happened in a variety of ways. The current transmission of the Pope appears to be very effective.
People want their worldly partner to be their eternal partner so they are not sinning with another person partner. This is why some spiritual people try to be celibate.
Jesus ends by saying you are greatly mistaken.
This is an excellent discussion on this issue.