Report: First-borns are smarter but younger siblings are more outgoing

A Long Island researcher is giving big brothers and sisters everywhere another reason to lord it over their younger siblings.

According to LiveScience.com, a study led by a doctoral candidate at Adelphi University found that first-borns are typically smarter -- even if younger siblings get better grades and are more outgoing.

Adelphi's Tiffany Frank said the findings shed light on the influence of sibling relationships.

"While parents might want to treat each child equally, it's almost impossible," Frank told LiveScience.com at the 118th Annual Convention of the American Psychological Association.

The study found that first-borns might score higher on tests because, at some point in their lives, they were the sole recipients of their parents' attention. Younger siblings, however, might earn better grades, because they received mentoring from first-born children.

Previous studies looked at children from different families -- including U.S. presidents, Nobel Laureates and NASA astronauts -- and found that many were first-born children, including 21 of the first 23 astronauts, LiveScience.com said. But those studies never looked at the effects of sibling rivalries and relationships. 

In the current study, according to LiveScience.com, Frank and her colleagues surveyed 90 pairs of siblings in high school and examined their grades, work ethic and overall academic performance.

A second experiment was done to examine personalities of 76 pairs of siblings. Later-born siblings were found to be more extroverted (sociable, outgoing), sentimental, forgiving and open to new experiences than their older siblings, LiveScience.com said.

First-born children were found to be more perfectionistic than their younger siblings.