Study: Oldest siblings have highest IQs

AMSTERDAM, Netherlands, April 12 (UPI) -- First-born children usually are smarter than their siblings, a Dutch study indicates.

A study of 1,000 children whose IQs were monitored from the time they were adolescents until they were 18, suggests that siblings' IQs are influenced by the order they are born, The Times of London reported.

The study, which appeared this week in the journal "Intelligence," revealed that older siblings had higher IQs in a majority of cases.

This study reportedly is the most recent to indicate that children's birth orders may strongly influence significant human characteristics, such as cancer risks, asthma, weight and even life span.

Scientists have also suggested birth order could affect which hand a child uses to write, sexual orientation and the number of people someone has sex with throughout their life.