Twins
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Fascinating Things We've Learned from Twin Studies

Updated November 5, 2019 4.4k votes 1.0k voters 84.7k views13 items

List RulesVote up the most fascinating things twin studies have taught us

About 3 out of every 100 births in the United States yields twins. Studying twins is a way for scientists to determine how much of our characteristics are influenced by genetics, since identical twins share nearly 100 percent of their DNA, whereas fraternal twins or normal siblings only share about 50 percent. This list is full of the most interesting twin study findings, and you might be surprised by how significant a role genetics play in determining your future.

These interesting twin studies also give us insight into how human beings interact with one another. Vote for what you think is the coolest twin study discovery.
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    Social Behavior Starts in the Womb

    Scientists who have studied twins in utero have noticed that they started to reach out to each other as early as 14 weeks into the pregnancy. They begin to caress each other and touch each other's mouths and eyes. Scientists say these observations lead to the conclusion that social behavior can emerge even before birth.
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    Genes Influence Our Name Preference

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    Okay, so there really isn't enough data to support this claim, but Thomas Bouchard's famous 1979 study on twins separated at birth includes a fascinating anecdote about names. A pair of male twins separated at birth and reunited at age 39 found that they had both married women named Linda; both divorced, and then both married women named Betty. One named his son James Allan, and the other named his son James Alan. They also both had pet dogs named Toy.
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    Gender Identity Is Genetically Determined

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    Twin boys Bruce and Brian Reimer didn't consent to participating in a case study on gender. Their parents volunteered them, after an accident during what should have been a simple circumcision left Bruce with significant injuries to his genitals. Dr. John Money, who believed that gender was entirely determined by upbringing, suggested that Bruce's parents raise him as a girl.

    The parents took the doctor's advice, and Bruce became Brenda. The experiment seemed to go just as Dr. Money planned, until Brenda became a teenager. She became depressed and then suicidal. To save her, her parents told her that she had been born a boy, and from that point on, she decided to live life as a man.
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    Most Personality Traits Are Inherited

    When scientists compared the personality traits of twins who were raised together against those who were raised apart, they found that the personalities of twins who were raised apart were more similar than they expected. The researchers concluded that personality traits are mostly determined by genetics. Interestingly, the traits most strongly determined by heredity are leadership and obedience to authority.
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