The major theme that Arundhati Roy's The God of Small Things and Toni Morrison's Song of Solomon share is that of incestuous relationships. In Song of Solomon, the protagonist, Milkman Dead, is nicknamed so after one of his father's employees sees him nursing from his mother. The reason the incident sparked such a nickname is the fact that Milkman is four years old at the time. He and Ruth are meant to feel shame...
The major theme that Arundhati Roy's The God of Small Things and Toni Morrison's Song of Solomon share is that of incestuous relationships. In Song of Solomon, the protagonist, Milkman Dead, is nicknamed so after one of his father's employees sees him nursing from his mother. The reason the incident sparked such a nickname is the fact that Milkman is four years old at the time. He and Ruth are meant to feel shame that Milkman wasn't weaned from the breast long ago. Because his nickname sticks, the shame of the incident also sticks to Milkman throughout the novel. Additionally, Milkman's father (Macon Dead II) grows suspicious of his wife's relationship with her own father. While it's not clear whether Ruth's relationship with her father was ever incestuous, she does idealize her father; the suspicion of incest with him affects her family relationships.
Incest is the engine of the plot in The God of Small Things. Rahel and Estha, twins and co-protagonists, are very close in their childhoods and seem to have the extrasensory perception often ascribed to twins. When Rahel marries, she and Estha are apart for several years, though their fondest memories are of each other. When they reunite, as adults, they have consensual sex and are happy about it, when up until this point they have both been unhappy. A symbolic reading of this act in the novel could suggest that the world can only be in balance through the harmony of yin and yang.
Other themes that both novels share are themes around ghosts of the past, violence, the legacy of ancestors, oppression, and the bonds of shared culture.