As the epigraph to Joanna Hershon's new novel explains, "dual inheritance theory…was developed in the late 1970s and early 1980s to explain how human behavior is a product of two different and interacting evolutionary processes: genetic evolution and cultural evolution." As the title suggests, the book is, in part, an illustration of that very phenomenon, as it strives to illustrate the character of a generation through two very different friends. The "dual" component of the title also refers to these friends themselves --- to the ways in which the two men's lives unfold in tandem, sometimes intersecting, for better or for worse.

"Hershon's novel is a thoughtful consideration of both a generation and of two individual members of it."

Ed Cantowitz and Hugh Shipley meet during their senior year at Harvard, in an encounter largely engineered by Ed, whose charisma and bluster overcomes Hugh's natural reticence and inclination to shy away from social interactions. Hugh comes from a traditional old-money Harvard family, the kind with a huge home in the wealthy Boston suburb of Brookline and an equally expansive house on the shore. As for Ed, he has grown up in the working-class Boston neighborhood of Dorchester, a Jewish kid at a time when that was still a major obstacle to acceptance and success. Ed longs to "make some real dough," while Hugh --- perhaps in an attempt to deny his privileged background --- just wants to make a difference in the world. The two young men have nothing in common, besides their forthcoming Harvard diplomas and the loss of their mothers. These facts alone serve to bring them together for a series of close-knit, if at times awkward, encounters during the remainder of their senior year and the summer that follows.

A DUAL INHERITANCE starts in 1962 and extends until nearly the present day. Early chapters, especially those in the first major section, read almost like stand-alone short stories or at least very well-developed vignettes. There are two particularly memorable fish-out-of-water scenes, one in which Ed drags Hugh to Dorchester to visit his decidedly uncomfortable father, and the other in which Hugh brings Ed along to the summer home of Hugh's girlfriend's family. Some events are set in motion that will affect the course of both men's lives. Subsequent sections follow them as they pursue very different definitions of success: Ed enters the world of finance and begins to make some real dough. Hugh, enabled by his trust fund, travels to Africa and then Haiti to pursue a life of studying, and later helping, native people.

As time passes, the narrative naturally shifts focus from Ed and Hugh to their daughters, whose friendship that started at boarding school begins to bring to light what caused Ed and Hugh to grow apart decades earlier. In these sections, the book's pacing picks up considerably, often jumping ahead a year or more in between paragraph breaks. Some readers may miss the deliberateness of the earlier sections, while others will welcome the quickening of the pace here.

Hershon's novel is a thoughtful consideration of both a generation and of two individual members of it. Beginning the story with a chance encounter on the Harvard campus and gradually unraveling everything that follows results in a leisurely but fascinating exploration of the parallels --- and points of intersection --- in two very different lives.