What is the role of hereditary disease in A Doll House?

Hereditary syphilis is the central theme of another play by Ibsen, "Ghosts" but plays only a minor role in "A Doll's House." Only one character in "A Doll's House" has what might be considered a hereditary illness, namely Dr. Rank, a close friend of Nora, who has contracted spinal tuberculosis. This disease, sometimes also known as Pott's disease, results in degeneration of the vertebrae leading to paraplegia. Although there is some slight degree of hereditary...

Hereditary syphilis is the central theme of another play by Ibsen, "Ghosts" but plays only a minor role in "A Doll's House." Only one character in "A Doll's House" has what might be considered a hereditary illness, namely Dr. Rank, a close friend of Nora, who has contracted spinal tuberculosis. This disease, sometimes also known as Pott's disease, results in degeneration of the vertebrae leading to paraplegia. Although there is some slight degree of hereditary predisposition to this disease, it is in fact an infectious disease, normally contracted in the same manner as other forms of tuberculosis. One might speculate that "spinal tuberculosis" in this play is being used as a euphemism and that when he wrote it in 1879 he was already thinking about hereditary syphilis which would be the theme of his in 1880 when he wrote "Ghosts". This identification of the disease is suggested by Rank's statement "My poor innocent spine has to suffer for my father's youthful amusements" which actually is more suggestive of neurosyphilis than tuberculosis. 

The concept of hereditary disease in the play is actually as much moral as physical. A major theme is that children suffer for the financial imprudence or moral weaknesses of their parents. Moreover, parents shape the characters and emotions of their children. Nora's relationship with Torvald explicitly echoes that with her father.