First Bite: How We Learn to Eat by Bee Wilson Read Free Book Online Page B

comes in so many guises, depending on the environment in which we happen to live. An innate appetite for the vitamin C in black currants would be of no use if you lived somewhere that black currants did not grow.
    In lab conditions, rats—our fellow omnivores—have shown a very erratic ability to self-select the diet that would do them the most nutritional good. In one study, rats were given a choice between a bad-tasting but protein-rich diet and a good-tasting but low-protein diet. Over the course of a week, fourteen out of eighteen rats failed to develop a preference for the food that would have done them the most good, and they lost weight. Other trials have attempted to find out whether rats could “self-select” to correct certain vitamin deficiencies, and concluded that many of them could not. With thiamine-deprived rats, the process of learning to like a thiamine-rich diet took a week or more, and the rats that did not adapt quickly enough to the correct food died. As for human subjects, there is, notes one specialist in the field, no data to suggest innate appetites for specific foods. It does seem possible for humans to learn over time specific appetites that will correct certain imbalances—particularly a craving for salt when lacking in sodium—but that is a different matter.
    Ninety years after Davis’s experiment, the view that likes are predominantly innate—or genetic—looks shaky. When trying to get to the bottom of where tastes come from, scientists have often turned to twins. Ifidentical twins share more food likes than nonidentical twins, the chances are that there is a genetic cause. Twin studies suggest that many aspects of eating are indeed somewhat heritable. Body composition—measured as body mass index, or BMI—appears to be highly heritable in both boys and girls. So is dietary “restraint,” or the mysterious urge to resist eating the thing you want to eat. But studies that look at likes and dislikes are much less conclusive. Several twin studies have suggested that identical twins are more likely to enjoy the same protein foods than nonidentical twins, but when it came to snacks, dairy, and starchy foods, their likes were only marginally more similar than those of the nonidentical twins. Overall, the evidence for tastes being heritable is very modest, accounting for only around 20 percent—at most—of the variation in foods eaten.
    Genes are only ever part of the explanation for what we choose to eat. As one senior doctor working with obese children put it to me, you could be cursed with all the genes that make a person susceptible to heart disease and obesity and still grow up healthy, by establishing balanced food habits. “ All of it is reversible ,” he said. Parents and children resemble each other no more in the foods they like than couples do, suggesting that nurture—whom you eat with—is more powerful than nature in determining food habits. Whatever our innate dispositions, our experience with food can override them. Maybe the reason you share your parent’s hatred of celery is that you have seen them recoil from it at the dinner table. Researchers found that when they gave three groups of preschool children different varieties of tofu—one group had plain tofu, one ate it with sugar, and one with salt—they quickly came to prefer whichever one they had been exposed to, regardless of their genes. It turns out that, so far from being born with genetically predetermined tastes, our responses to food are remarkably open to influence, and remain so throughout our lives.
    If you want to know what foods a person does and does not like, the single most important question you can ask is not “What are your genes?” but rather “Where are you from?” Had he lived in a part of the world where cornflakes are hard to come by, the cornflake boy would have had to find another way to annoy his parents. To a large extent, children eat—and therefore like—what’s in front of