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 ...

Back when they were single, identical twins sisters Venessa and Kerissa Sealby never dreamed they would marry identical twin brothers. Then they met Lucas and Jacob Sealby. During a March 29 ...

Their children are genetic siblings, known as quaternary twins. After identical twin sisters from Delaware married identical twin brothers from Tennessee, the children they are raising together share ...