The following version of the book was used to create this study guide: Mukherjee, Siddhartha. The Gene: An Intimate History. Scribner, 2017. Amazon Kindle Edition.

In the prologue, author Siddhartha Mukherjee writes about his family history of mental illness and connects this personal story to his larger questions about the nature of genes, genetics, and heredity. He outlines this book as "the story of the birth, growth, and future of one of the most powerful and dangerous ideas in the history of science: the 'gene'" (9).

Part One covers the years between 1865 and 1935 and focuses on the early discovery of genes as well as the initial development of modern theories on evolution and heredity. Mukherjee writes about some of the forefathers of these sciences including Charles Darwin and Gregor Johann Mendel. He also touches on theories of genetics and heredity from Antiquity and the Middle Ages, thus providing a complete overview of historical theories on the nature of inheritance.

Part Two spans the period between 1930 and 1970 and focuses on the mechanism of inheritance. Once the existence of genes was identified in the previous section, the next task for scientists was to deduce how genes function on a mechanistic level. This section focuses on social as well as scientific ideas about genetics. Mukherjee writes about various eugenic ideologies, including the contrasting examples of Nazi Fascism and Soviet Communism. He then turns to post-World War Two scientific endeavors to identify the nature of the gene molecule and how it functions. This includes identification of the structure and functions of DNA, RNA, and how they encode amino acids and proteins.

Part Three focuses on late 20th century scientific developments in the fields of sequencing and cloning genes, and spans the years 1970-2001. This section overlaps chronologically with Part Four, which spans the years 1970-2005 and focuses more specifically on human genetics. The sciences of sequencing and cloning genes have significant ramifications and implications for the possibility of manipulating human genes. The development of genetic screening also has serious implications for the potential treatment of genetic conditions and/or predispositions. Together, Parts Three and Four outline the science and potential ramifications—positive and negative—of mapping and modifying genes. Mukherjee uses examples, including that of Huntington's disease, to demonstrate how the science of genetic mapping and screening has advanced over the second half of the 20th century, culminating in the Human Genome Project, which at the turn of the millennium succeeded in mapping the entire human genome, providing a normative baseline for our understanding of our genetic code.

Part Five spans the years 2001-2015, bringing the reader up to the contemporary period of the book's publication. This section focuses on the ramifications of genetic science, with an emphasis on "the genetics of identity and 'normalcy'" (327). Mukherjee writes about some of the conclusions of the human genome project, as well as contemporary understandings of how genes and the environment work together to determine things like gender, sexual orientation, and psychological impulses. Mukherjee also writes about the science of epigenetics, which begins to account for how environmental factors and external triggers can influence an individual's genome.

Part Six is a look toward the future and an exploration of the potential for genetics, gene therapies, genetic screening, and gene manipulation technologies. Mukherjee writes about what genetic screening for complex hereditary illnesses may mean for the individual and for society as a whole. He also speculates about the ethics of developing genetic technologies and invites readers to consider the potential future directions of the field.

In the epilogue, Mukherjee invites readers to imagine a future in which genetic technologies have changed many aspects of society. Mukherjee emphasizes the positives and negatives of these scenarios, writing "it inspires both wonder and a certain moral queasiness" (491).