Are Jesus' Siblings Children From Joseph's Previous Marriage?

The best book I've read on the subject of Mary's perpetual virginity (and Marian issues more broadly) is Eric Svendsen's Who Is My Mother? (Amityville, New York: Calvary Press, 2001). On the patristic evidence related to whether Mary was a perpetual virgin, see here. In case this information would be helpful to anybody, here are some comments I recently made about the perpetual virginity doctrine in an email exchange with a couple of people:

One of the most important concepts to focus on when thinking about this issue is what other options were available to the authors in question. What other language could they have used? For example, Luke refers to Jesus as Mary's "firstborn" (2:7), even though elsewhere he uses a different term for "only born" (7:12, 9:38). Why would Luke use a term that seems to contradict Mary's perpetual virginity when he was aware of an alternative term that's consistent with perpetual virginity and uses it elsewhere in his gospel? Similarly, why does Luke differentiate between "brothers" and "relatives" in 21:16 if there's no significant difference between the two? In the same way, why does Hegesippus refer to Symeon as Jesus' "cousin" (in Eusebius, Church History, 4:22:4), yet refer to James as Jesus' "brother" (ibid., 2:23:4) and Jude as Jesus' "brother according to the flesh" (ibid., 3:20:1)? We see this over and over again with the earliest sources. They not only use language that seems to contradict the perpetual virginity of Mary, but even use different language elsewhere that's consistent with perpetual virginity, which they could have used in the passages relevant to Mary….

Since Josephus is among the early sources who seem to contradict the perpetual virginity of Mary, we can sum up the evidence by saying that the doctrine is inconsistent with the most natural reading of a few New Testament authors, the earliest patristic sources to discuss the topic, and the earliest non-Christian source to address the subject….

By the way, Svendsen also addresses the view that the brothers were children of Joseph from a former marriage. It's subject to some of the same criticisms as the view that the brothers were cousins or some other more distant type of relative (Matthew 1:25, Luke 2:7, the term "brother" more often refers to biological siblings, etc.). Another problem with the view is the absence of the siblings in the infancy narratives. I discuss multiple ways in which their absence is problematic in an article on Matthew and Luke's agreements in the infancy narratives:

http://triablogue.blogspot.com/2013/11/agreement-between-matthew-and-luke.html

One of the points I make there is one I don't recall Svendsen or anybody else making. It's often claimed that the infancy narratives are meant to parallel Jesus to Old Testament figures. Yet, two of the most significant figures Jesus allegedly is being paralleled to in the New Testament, Moses and David, had older siblings who played a large role in their lives. Moses' older sister even has a prominent role in the Exodus account of Moses' birth. If Matthew and Luke (and other sources) were paralleling Jesus to figures like Moses and David, it would have been in their interest to have mentioned older siblings. Instead, both infancy narratives imply that Mary gave birth to more children (Matthew 1:25, Luke 2:7), and both leave out any reference to older siblings when the family and their moving from one location to another are described (e.g., "take the child and his mother" in Matthew 2:13).

Any argument that the siblings were old enough at the time to be living apart from Joseph and Mary would run into the problem of offering a weaker explanation for how long the brothers of Jesus lived and were highly active (e.g., 1 Corinthians 9:5, James' death by martyrdom in the 60s while serving as a leader of the Jerusalem church and one of the most prominent apostles). Maybe Jesus' brothers lived unusually long and were highly active at such an old age. But the alternative view that they were younger siblings of Jesus offers a better explanation of the evidence. It's yet another example of how upholding Mary's perpetual virginity requires us to adopt less likely explanations of the evidence on issue after issue after issue.