The Gene: An Intimate History - Siddhartha Mukherjee Page 0,163

with races, tribes, or subpopulations. Intelligence and temperament are not marathon races: there are no fixed criteria for success, no start or finish lines—and running sideways or backward, might secure victory.

The narrowness, or breadth, of the definition of a feature is, in fact, a question of identity—i.e., how we define, categorize, and understand humans (ourselves) in a cultural, social, and political sense. The crucial missing element in our blurred conversation on the definition of race, then, is a conversation on the definition of identity.

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I. Wilson drew his crucial insight from two giants of biochemistry, Linus Pauling and Émile Zuckerkandl, who had proposed an entirely novel way to think of the genome—not just as a compendium of information to build an individual organism, but as a compendium of information for an organism’s evolutionary history: a “molecular clock.” The Japanese evolutionary biologist Motoo Kimura also developed this theory.

II. If the origin of this group was in southwestern Africa, as some recent studies suggest, then these humans traveled largely east and north.

III. More recent estimates have pinned the correlation between identical twins to 0.6–0.7. When the 1950s data was reexamined in subsequent decades by several psychologists, including Leon Kamin, the methodologies used were found to be suspect, and the initial estimates called into question.

IV. There can hardly be a more cogent genetic argument for equality. It is impossible to ascertain any human’s genetic potential without first equalizing environments.

The First Derivative of Identity

For several decades, anthropology has participated in the general deconstruction of “identity” as a stable object of scholarly inquiry. The notion that individuals craft their identity through social performances, and hence that their identity is not a fixed essence, fundamentally drives current research into gender and sexuality. The notion that collective identity emerges out of political struggle and compromise underlies contemporary studies of race, ethnicity and nationalism.

—Paul Brodwin, “Genetics, Identity, and the Anthropology of Essentialism”

Methinks you are my glass, and not my brother.

—William Shakespeare, The Comedy of Errors, act 5, scene 1

On October 6, 1942, five years before my father’s family left Barisal, my mother was born twice in Delhi. Bulu, her identical twin, came before her, placid and beautiful. My mother, Tulu, emerged several minutes later, squirming and crying murderously. The midwife must, fortunately, have known enough about infants to recognize that the most beautiful are often the most damned: the quiet twin, on the edge of listlessness, was quite severely undernourished and had to be swaddled in blankets and revived. The first few days of my aunt’s life were the most tenuous. She could not suckle at the breast, the story runs (perhaps apocryphally), and there were no infant bottles to be found in Delhi in the forties, so she was fed through a cotton wick dipped in milk, and then from the caul of a cowrie shell shaped like a spoon. A nurse was hired to tend to her. When the breast milk began to run dry at seven months, my mother was quickly weaned to let her sister have its last remnants. Right from the onset, then, my mother and her twin were living experiments in genetics—emphatically identical in nature and emphatically divergent in nurture.

My mother—the “younger” of the two by minutes—was boisterous. She had a slippery, mercurial temper. She was carefree and fearless, fast to learn and willing to make mistakes. Bulu was physically timid. Her mind was more agile, her tongue sharper, her wit more lancing. Tulu was gregarious. She made friends easily. She was impervious to insults. Bulu was reserved and restrained, quieter and more brittle. Tulu liked theater and dancing. Bulu was a poet, a writer, a dreamer.

Yet the contrasts only highlighted the similarities between the twins. Tulu and Bulu looked strikingly similar: they had the same freckled skin, almond-shaped face, and high cheekbones, unusual among Bengalis, and the slight downward tilt of the outer edge of the eye, the trick that Italian painters used to make Madonnas seem to exude a mysterious empathy. They shared the inner language that twins often share. They had jokes that only the other twin understood.

Over the years, their lives drifted apart. Tulu married my father in 1965 (he had moved to Delhi three years earlier). It was an arranged marriage, but also a risky one. My father was a penniless immigrant in a new city, saddled with a domineering mother and a half-mad brother who lived at home. To my mother’s overly genteel West Bengali relatives, my father’s family was the very embodiment of East