How does the author use doubling in the novel, The Gold Bug Variations?

It is not accidental that Powers elects to make his two pairs of major characters each four years apart in age. This double pair suggests the double helix to which the number four is fundamental. The novel's double love story reinforces this notion and relates it to Johann Sebastian Bach's inventions as well as to such disparate details as the four chambers of the heart, the four winds, the four seasons, and the so-called four corners of the earth.