Why, in the Gospel of Mark, is Jesus referred to as the son of Mary but, in the Gospel of Luke, he is referred to as the son of Joseph?

Why, in the Gospel of Mark, is Jesus referred to as the son of Mary but, in the Gospel of Luke, he is referred to as the son of Joseph? >Is not this the carpenter, **the son of Mary**, the brother of James, and Joses, and of Juda, and Simon? and are not his sisters here with us? And they were offended at him. (Mark 6:3) >And all bare him witness, and wondered at the gracious words which proceeded out of his mouth. And they said, **Is not this Joseph's son?** (Luke 4:22)