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 ...

For the best experience, please enable JavaScript in your browser settings. Following the Kakamega twin puzzle that has drawn the attention of the entire country, we ...

Although there are some rare exceptions, identical twins are almost always the same sex. Because identical twins occur when a single fertilized egg splits and forms two embryos, each embryo has the ...

You've probably heard of identical and fraternal twins, but a report published Thursday says there's a third kind -- sesquizygous twins or "semi-identical." Identical -- or monozygotic -- twins pop up ...

The Science of Siblings is a new series exploring the ways our siblings can influence us, from our money and our mental health all the way down to our very molecules. We'll be sharing these stories ...

Sam and John Fetters are identical twins with autism. But Sam is in college, while John still struggles to form sentences. Their experience may... These identical twins both grew up with autism, but ...