It seems to me that, on the one hand, to suggest that Mark's readers would have thought he did not have a human father is to make too much of silences. As a rule, we assume that people have fathers, even when we don't mention them, and it seems to me that an exception to that rule would have required an explicit claim rather than silence. And while it is common for commentators to suggest that "son of Mary" reflected rumors that Jesus was illegitimate and his father unknown, that too seems to be reading too much into Mark's language, which is not followed by any defence of Jesus' legitimacy.Well, James may be right, but the difficulty is that the Gospel itself does not provide the necessary clues, and this is where Matthew's (and several scribes') "orthdox redaction" comes in. I am not suggesting that the author of Mark's Gospel thought that Jesus had no earthly father. I don't know what the author of Mark thought because he does not tell us. That is the difficulty with "silences". The absence of key information invites the reader to speculate. And in the case of Mark's Gospel, the person that I called "the unwary reader" might well assume that Jesus had no earthly father. He is not named in key contexts when one would expect him to be named, like when Jesus is first introduced in Mark 1, or when his family is first mentioned in Mark 3.21 and 3.31-34, or when Jesus returns to his patris in Mark 6.1-6, and members of his family are named. And, moreover, there are repeated references to another father, Abba Father, who addresses Jesus as his son, and who addresses others about his son.
So the way that I look at it is that the invitation is there to read Mark in a certain way. And Matthew, Mark's first reader, is a careful reader and is attentive to possible mis-readings (as he sees them) and he makes sure that they are corrected. And the genius of Matthew's Gospel is that he was largely successful in this project.
Nevertheless, James is right to draw attention to the oddity of Matthew's own answer to the question of Jesus' parenting. He affirms the genealogy through Joseph right at the outset of the Gospel (Matt. 1.1-18), something he affirms elsewhere too (Matt. 13.55), but then he sticks right next to it a story that is usually read as affirming a virginal conception (Matt. 1.18-25). The addition of the latter only serves to underline the point, however, about Matthew's "orthodox redaction of Mark". It is this story, and the tension it throws up between simultaneously affirming Jesus' human parents and his divine origin that finds its way into Christian orthodoxy. And in this Luke too, following Matthew's lead, plays a key part.