The new novel "Sisterland" by best-selling author Curtis Sittenfeld tells the story of twin girls who have a psychic connection. Though it's a fictional story, it draws upon a common belief that twins share some sort of unexplained mental or spiritual connection. It's an intriguing idea, but what's the truth behind it?
About one out of every 30 babies born in the United States is a twin. Identical twins are of particular interest to scientific researchers because they help control for genetic variation between patients in studies. It's not surprising that identical twins share much in common, since they have the same DNA. Scientists know that what makes us who we are - including, to some degree, our intelligence, personal preferences, and so on - is part nature and part nurture, a combination of heredity and environment.
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Stories about mysterious connections between twins - and especially identical twins - are ancient and legion. Some say twins share some psychic connection, or even feel each other's pain. There are stories of twins who happened to give birth to baby daughters on the same day, completely by chance, and twins who were separated at birth but reunited years or decades later to find that they both married spouses with the same name and drive identical cars. Psychic powers have never been scientifically proven to exist, and psychic twins are no exception. However as we move way from science toward anecdotal evidence, we find intriguing parallels between twins.