Identically Different

June 3, 2013
Spector, a genetic epidemiologist, has a wealth of case studies to draw from for his research on genes and epigenetics (the mechanism by which nongenomic elements affect genes): he’s the founder and director of the TwinsUK registry, home to data on over 12,000 pairs of twins. He’s spent the past two decades studying genetically identical siblings; for 17 of those years, he ascribed to the “gene-centric” view of things. But he felt like he was “missing something.” That turned out to be the concept of “acquired inheritance,” whereby environmental, hormonal, or other external stimuli modify one’s genetic makeup. Perhaps the most interesting consequence of this is that such an altered blueprint can then be passed on to future generations. But drastic changes can occur even within one’s own lifetime. For example, a cabdriver in London is subjected to intense route training in order to navigate the city’s intricate streets; as a result, his hippocampus—a part of the brain that deals with spatial navigation—becomes enlarged. However, upon retirement, the cabbie’s hippocampus will likely shrink. Spector’s research has far-reaching implications in fields as diverse as oncology and parenting, and it provides a new perspective on the age-old nature-vs.-nurture debate—turns out they may be on the same team. Agent: Sophie Lambert and Kevin Conroy Scott, Tibor Jones & Associates (U.K.).

Starred review from June 1, 2013
Genes dictate our anatomy, emotions and behavior, except when they don't, according to this ingenious account of how inheritance and environments--including our parents' environment--vie to make an individual. Physician and TV commentator Spector (Genetic Epidemiology/King's Coll. London; Your Genes Unzipped, 2003) fills his book with entertaining anecdotes of identical twins (he is director of the world's largest twin registry) and examples from popular culture to make a convincing case that inheritance is more complicated than we think but no less fascinating. The idea that genes make us what we are ruled for half a century, until the 1960s, when a revolutionary generation insisted that our environment makes us what we are. Nowadays, scientists agree that both have an influence, but Spector cautions that DNA does not hardwire our lives. It turns out that actions can physically alter genes and that--despite what we learned in biology class--we can pass acquired traits to our children or even grandchildren. This process, epigenetics, means, for example, that a person who overeats transmits the risk of obesity for several generations. Genetics turns up in surprising places. Identical twins raised apart have remarkably similar personalities, sharing qualities such as optimism, empathy and a sense of humor (or lack thereof). Environmental factors also deliver plenty of surprises. Most readers will squirm to learn that upbringing exerts remarkably little influence on how children turn out. They are far more likely to emulate their friends than their parents, however competent and loving. Abusive parents are a different matter; crime, abusive behavior and mental illness have a disturbing tendency to run in families. A delightfully thought-provoking overview of the nature-vs.-nurture debate.

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