When Aunt Phyllis tells Cassandra, “What I’m about to tell you is our family’s big secret. Every family’s got one, you can be sure of that. Some are just bigger than others” (20), she’s expressing a central theme of the novel. Family secrets loom large in the history of the Mountrachet family. Every major character in the book has something to conceal. Hugh’s initial disclosure to Nell that she’s adopted is merely the tip of the iceberg.

Georgiana’s identity, and that of her children, is meant to be kept secret so she can protect herself from Linus. Linus harbors an unnatural attraction toward his sister, her daughter Eliza, and his grand-niece, Ivory. Eliza never tells anyone that she’s borne a baby for Rose. Later, she tries to keep Ivory’s whereabouts a secret so that the Mountrachets will never find her. Rose is so fearful of her daughter’s true parentage becoming known that she wants to relocate the entire family to America. Adeline doesn’t want anyone to recall that she comes from a working-class family. Nathaniel comes from a similar background, and Adeline does her best to cover that up, too. Finally, Adeline conceals Eliza’s death by burying her in an unmarked grave while she simultaneously stages a mock funeral for the still-living Ivory.