One blueprint, two souls. How do you become your own person when there is someone else—your twin—who is exactly the same?

Abigail Pogrebin is a mother, a New Yorker, a writer, a daughter, and a wife, but the role that has most defined her, she knows, is that of identical twin. In One and the Same, she weaves her quest to understand how genetics shape us into a memoir of her own twinship. What does it mean to have a mirror image? How can you be one, singular, unique, as we all like to think we are, when somebody shares your DNA?

In One and the Same Abigail crisscrosses the country and travels the world to explore the relationship between twins, which can range from passionate to bitterly resentful. She interviews football stars Tiki and Ronde Barber, who admit their twinship comes before their marriages;bawdy, self-proclaimed “twin ambassadors” who have created a media business around their twinness; sisters who stopped speaking for three years;and brothers whose shared genetic anomaly wrought unspeakable tragedy.She explores the new science of epigenetics, which shows how the same DNA can yield different results—a moody twin, a happy twin, one who gets cancer, one who doesn’t. She speaks to the twins experts and tries to answer the question parents of twins ask most: Is it better to encourage their closeness or separateness?

Threaded throughout One and the Same are Abigail’s own memories of a buoyant childhood growing up with her twin sister and best friend, Robin. “The Pogrebin Twins” were outgoing, cheerful and hammy, very much alike, and effortlessly close. But hey don’t have the same intimacy anymore, and Abigail traces the bittersweet process of growing apart from someone she thinks of as part of herself.

This is a riveting portrait of twin life by an accomplished journalist who exposes twinship from the inside. It yields fascinating truths about how we become who we are and about the struggle for singularity that defines us all.