I hardly believed they were twins! Several years ago, one of my developmental psychology students told me that she had a fraternal twin sister who looked nothing like her, and it turned out that she ...

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 ...

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 ...