Sibling rivalry

According to “The New Science of Siblings” first-borns are tougher than their younger siblings. TIME put together a gallery of famous Brothers and Sisters, featuring a lot of professional athletes:
The DiMaggios
The Ripkens
The Williams Sisters
The Mannings

Today’s Christian published a Bible Quiz on Biblical Siblings. The Bible records some bitter sibling rivalries, such as the one that led Cain to murder his brother Abel. And yes: Cain was the first-born.