Sarah and Aimee Charlwood from Brisbane, Australia, are identical twins. They didn't spend a day apart from when they were born until they were 16 years old. Eerie coincidences happen to them, but ...

For more than a century, scientists have debated whether intelligence is mostly a product of nature or nurture. Identical twins—those born with the same genetic blueprint—have long been the perfect ...

Identical, or monozygotic, twins develop from the same fertilized egg that splits into two. These twins are the same sex and share the same genes. Sometimes called paternal twins, identical twins ...

Epigenetics and differences in prenatal hormone exposure can help explain how two people can share the same DNA, but not necessarily share the same sexuality.