How Firstborns Get Smarter

In the wake of the study released last week on intelligence and birth order, parents and social scientists are scrambling to explain why firstborns score an average of three IQ points over subsequent children. Theories range from the role older children play as tutors to younger sibs to the notion that adding a child may diminish the family’s  "intellectual environment." 

Relevant dynamics may also include the tendency of families to label each child: the family cut-up, the klutz, the whiner, the New York Times notes. Eldest children tend to be tagged the most responsible. When asked what parents should do about this, one psychologist answers: nothing. “Younger siblings are more likely to take chances,” he adds. (More intelligence stories.)