Educational Media Reviews Online

When the Human Genome Project was completed in 2003, scientists believed that with the DNA sequence of all human chromosomes in hand they would be able to identify and cure heritable diseases. However, their optimism has been dampened by cases of identical twins, only one of which develops a disease, such as autism or cancer. Since identical twins have identical DNA, what could possibly be causing a disease in just one twin?

This is the conundrum provokingly presented at the beginning of Ghost in Your Genes. The answer is the epigenome, a network of molecules that regulates the expression of the genome. Biologists are beginning to understand how this system of proteins, methyl markers and other molecules turns on harmful genes or turns off helpful ones. The epigenome is the interface between the genome and the environment; events in the environment or a person's lifestyle trigger a response in the epigenetic molecules that regulate the expression of genes. The power of the epigenome is driven home by a study of archives in a small Swedish village that had experienced cycles of plenty and famine over the decades. After studying harvest records and birth and death records, biologists discovered a pattern - the availability of food during a grandparent's childhood affected the longevity of his or her grandchildren. The epigenetic molecules can mark DNA in response to plenty or famine, be passed onto children and control DNA expression two generations later!

The intriguing epigenome is presented using interviews and graphics, making it accessible, understandable and engaging for the general audience. While a mother describes the profound differences between her identical twin daughters, the viewer sees the daughters engaged in their normal activities. One preteen daughter is setting the dinner table and chatting with her mother, while the other stares at a computer screen and compulsively cleans it. The second daughter, despite having identical DNA with her twin, is autistic. Several scientists describe the genetic puzzles that prompted their studies and explain how they started to tease out the existence and functioning of the epigenome. Colorful, 3-D graphics depict DNA molecules and demonstrate how methyl markers and other molecules can bind to the genes and regulate their expression. Antique photographs of farmers in their fields and family gatherings accompany and humanize the discussion of the study of transgenerational inheritance in the Swedish village.

Ghost in Your Genes is an appropriate documentary for viewers who know the basics of genetics. High school and college students will have enough background to follow the explanations of the discovery and workings of the epigenome. Adults in the general public who are interested in genetics would also enjoy finding out about this added layer of complexity in human biology. Ghost in Your Genes would be an outstanding choice for the culmination of a film series on the history of genetics and the discovery of DNA.