In this new book, Dr. Sharon Moalem leads the reader through the personal stories of men, women, and children with genetic diseases in order to argue that it is the interplay of nature and nurture that can most accurately explain basic human biology. Through these cases, he details “what our genes do to us and what we do to our genes,” giving the audience a better understanding of epigenetics and why each of us is more than just the sum of our individual parts. He is the author of several books, including Survival of the Sickest (2007) and How Sex Works (2009), as well as the cofounder of two biotechnology companies that focus on improvement of human health.

Moalem begins his most recent book by making analogies between our own past experiences, such as the “smell of the cafeteria on sloppy joe day” or “the ache of your first crush,” and how these encounters leave indelible marks in our DNA. Through these correlations, the reader is drawn in by believing that something relevant and significant about oneself will be revealed. Moalem’s description of epigenetics or “flexible inheritance” reveals not only that it is more than our genome sequence that is responsible for who we are, but that one can purposely alter the course of one’s life with simple lifestyle changes (after reading of the positive health effect of betaine in spinach at the genetic level, I predict that most readers will likely begin to include it in their daily diets). He emphasizes, multiple times, that very small changes often lead to drastic transformations in the state of one’s health. He demonstrates this idea primarily through the use of clinical case studies of people with inherited genetic diseases. He presents many examples gathered from his own experiences with his patients, leading the reader to appreciate that Moalem’s expertise comes through personal involvement rather than “book learning” alone. He even goes so far as to personalize this book by including the story of a friend who asked for the author’s surreptitious help in determining whether his fiancée carried the marker for Huntington’s disease (Moalem refused to help this friend collect the woman’s hair samples and sequence her DNA without her knowledge).

In a few instances, Moalem gives the reader the historical background behind the discovery of a particular disease. One such story is that of a Norwegian mother, Borgny Egeland, and her moving quest to rescue her two children, Liv and Dag, from their severe intellectual disabilities. This dedicated mother, certain that her children were not born with the infirmity, sought out the aid of a local physician-scientist, Dr. Asbjorn Folling. He, along with others over the next several decades, were able to identify the causative agent of the children’s problem – that is, an inability to break down phenylalanine because of the inherited metabolic disorder now known as “phenylketonuria.” Although too late to reverse the damage done to Liv and Dag, this work paved the way to saving millions of children to this day. At other times, Moalem uses unrelated historical references or ancillary analogies to introduce cases. Often, these are convoluted and might lead the reader astray. The cases themselves are well chosen and can stand on their own without such distractions.

I began this book thinking that Moalem’s goal was to describe epigenetics with regard to human health and medicine. Instead, I quickly realized that he was weaving together a connected and fascinating series of genetic tales in which he ultimately argues for the equal influence of nature and nurture in determining who we are and who we can become. Although writing for the layman, Moalem does not oversimplify the science to the point of being condescending. For readers with an interest in genetics, human health, and evolution, the book is an interesting and easy read that will lead them to seek out additional information on these topics.

ELIZABETH COWLES teaches freshman-level biology, biochemistry, and entomology at Eastern Connecticut State University. She has taught at the undergraduate and graduate college levels for over 20 years. Her interests include insect toxicology, protein characterization, and astrobiology. Cowles holds degrees in biology and biochemistry from Cornell University and Michigan State University. Her address is Department of Biology, ECSU, 83 Windham St., Willimantic, CT 06226; e-mail: