Spacing Siblings At Least Two Years Apart Makes Kids Smarter

Kasey Buckles' kids are two years, two months and two weeks apart. The timing is significant because Buckles, an assistant professor of economics at the University of Notre Dame, has just officially determined that the ideal spacing between an older and younger sibling is at least, you guessed it, two years -- at least when it comes to intelligence.

Older children who are born at least two years before a younger sibling's debut are smarter, according to research that is due to be published in an upcoming issue of the Journal of Human Resources. They score higher on math and reading tests than children born closer together.