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 ...

After identical twin sisters from Delaware married identical twin brothers from Tennessee, the children they are raising together share in a rare biological phenomenon. When identical twin sisters ...

Mono-mono twins are an incredibly rare type of identical twins who share both a placenta and an amniotic sac. While this makes for a high-risk pregnancy, advances in monitoring and treatment have ...

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 ...