Who Was Jesus' Grandfather?

Grant Osborne @ Christianity Today covers what the two genealogies of Christ, found in Matthew and Luke, are really trying to say.

He mentions: The Importance:

Genealogies fulfilled multiple purposes in the ancient world. Society was organized around kinship patterns, so every family needed lists that described their ancestral pedigree. Such family trees determined a person's social relationships. For instance, two families planning the marriage of their children would compare family lines to check kinship ties to ensure the two were "compatible." And rulers used genealogies to justify their power, rank, and status.

For the Gospel of Matthew:

Matthew arranges his genealogy into three groups of 14 names each. In Jewish gematria—a kind of numerology stemming from the fact that letters of the Hebrew alphabet were also numbers—names have numerical value. The three consonants for David add up to 14. So Matthew underscores Jesus' kingly ancestry by working in groups of David, or 14.

As for Luke:

Luke does not group the names like Matthew does but provides a simple succession of ancestors. The list contains many more common names (some of which we know nothing about) and seems to underscore Jesus' humanity as well as his divine sonship. Moreover, by going all the way back to Adam (the ancestor of all humanity), Luke maintains a universal thrust, emphasizing that Jesus came for all mankind. The list ends with Adam, and then Luke moves into the story of Jesus' encounter with Satan in the wilderness, in which Jesus rises above temptation as Adam did not. The message is clear: In Jesus, all human beings find their sins overcome.