coffee talk: jesus' family tree

I've got a theology question. Now don't run away because you don't feel qualified to talk theology. I'm not looking for expert advice. I'm looking for honest thoughts. And I know you have those to give me. So I hope you will.

The New Testament starts out with the genealogy of Jesus in Matthew 1.

I've heard that referred to countless times to show the legacy of those in Jesus' ancestry: Abraham's great faith, David's man-after-God's-own-heart-ness, Solomon's wisdom. I've also heard it used to show the unlikely characters that God used in Jesus' family tree, like Rahab the prostitute and Bathsheba the adulterer.

I love all that.

But this is where I get hung up: The genealogy ends with "...Jacob the father of Joseph, the husband of Mary, of whom was born Jesus, who is called Christ."

That's Joseph's family tree. And Joseph, while Jesus' earthly dad, wasn't His biological father. Jesus comes from Mary's bloodline, but not from Joseph's.

So how can Joseph's ancestors be listed as Jesus' family tree?

Any thoughts?