Why is moon determined to find Ricky's daughter and bring her back to America in the novel, Finding Moon?

The novel traces Moon's attempt to locate in Cambodia the child of Ricky, his deceased younger brother, and a Cambodian woman, now also dead. Moon is anxious to find the infant girl for many reasons—not the least of these being his mother's intense desire for a grandchild—but he is particularly concerned that the child will suffer because of her mixed parentage.