For more than a century, scientists have debated whether intelligence is mostly a product of nature or nurture. Identical ...

Identical twins who were raised apart may have IQ differences similar to those of total strangers, according to new research.

Sarah and Aimee Charlwood are identical twins. They didn't spend a day apart until they were 16. They share the same ...

After believing that her daughters were fraternal twins for so long, a mom was stunned when a genetic test revealed otherwise. Not long after Tamara Vanderent, 30, discovered that she was expecting ...

For decades, the fitness community has been torn: is high-fat or high-carb the ultimate fuel? A recent experiment put the age-old debate to the test using a pair of identical twins who share 99% of ...

From Romulus and Remus—the myth of the twin brothers who founded the city of Rome—to the synchronized speech of Australia's "Twinnies" Paula and Brigette Powers, identical siblings have long inspired ...