Around 1 in 250 pregnancies result in identical or “monozygotic” twins, but the mechanism behind monozygotic twinning has remained elusive, partly because the phenomenon is so rare and partly due to ...

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 ...

Twins are pretty rare, accounting for just 3% of births in the U.S. these days. But new research shows that for primates 60 million years ago, giving birth to twins was the norm. When you purchase ...