Bolded statement is false, outright. Here's one of the better things I've seen on the topic, nice and simple:
http://www.christianforums.com/t7632047/ Post #1
Ay yay yay. That gave me a headache. That video was so complicated.
Let me see if I got this right. Jacob is the biological father of Joseph, but Heli is the legal father of Joseph. Matthan is the biological father of Jacob. Matthan had married Esta, but he died and she married Mathhat.
There seems to be some jumping through hoops here. So the first genealogy given is the biological one. Joseph is still not the biological father of Jesus. The Deuteronomy law does not directly apply to Joseph. As far as I know, Joseph was Mary's first husband.
Joseph is the legal father but not the bloodline father. As far as I can tell, Jesus' tribal status and lineage would be from his birth father ... who is God.
I found sources saying they adoption is not valid for lineage or tribe. Descent goes through the biological father:
Matters relevant to the child's status are determined by the status of the birth parents, not by that of the adoptive parents. The child's status as a Kohein, a Levi, a Jew, and/or a firstborn, are all determined by reference to the birth parents.
Judaism 101: Birth and the First Month of Life
Any children of the marriage will take their tribal affiliation from their father, not their mother, just as their mother takes her status from her husband after marriage. If the couple adopt children, they will not automatically take on the Judaism of the mother, nor the tribal affiliation of the father.
Raise Your Hand If Youâre A Kohen - More Mitzvahs & Traditions
When an adopted child is born Jewish, the adoptive parents need to determine the child's tribal affiliation: Kohen, Levite, or Yisrael. If, for example, a male child is born a Kohen, traditional Jewish law forbids him from marrying a divorcee, even if his adoptive parents are not Kohanim.
Jewish Adoption in America - My Jewish Learning
Yahoo! Canada Answers - Is Jesus really descendant of King David?
(Scroll down to see Allon's answer, an orthodox rabbi. The other answers are pretty much nonsensical)