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 ...

Mallory Carlson's baby daughter Josie was diagnosed with a rare form of leukemia. Hours later, doctors discovered that her ...

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 ...

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 ...

Researcher Sophie Bell and professor Eric Turkheimer identified how genetics, environment and biology combine to affect ...