This passage is a significant piece of the puzzle in making sense of Mum’s death. Dad suggests that the tooth belonged to another man who caused Mum to leave. This coincides with Miles’s memory of being in Mum’s car surrounded by bags of clothes—she was likely leaving Dad permanently on the night of the accident. His addition of “because of you” subtly implies that Harry is likely the other man’s son rather than Dad’s. Harry’s response of “I’m glad” is the same response that Joe delivered to Dad when his father told him that he was “just like him” and broke Joe’s arm. This parallel could signify that Joe, too, is the son of the other man.