Birth order typically creates some form of sibling rivalry, but a new study suggests it also has an impact on personality and intelligence. A group led by Tiffany L. Frank, a doctoral candidate at Adelphi University in Long Island, N.Y., found that first-borns tend to be more intelligent, while younger siblings get better grades and are more outgoing, according to a LiveScience report.
For years, scientists have tried to determine what effect birth order has on a person's life. Past studies that looked at U.S. presidents, Nobel Laureates or NASA astronauts found that they were overwhelmingly first-borns. Other studies found that middle children are independent and inventive, while the youngest children are more carefree.
Frank and her colleagues, Hannah Turenshine and Steven J. Sullivan of Lawrence High School in Cedarhurst, N.Y., surveyed 90 pairs of siblings in high school. The siblings were asked to report their grades and rank themselves against their siblings on academic performance, work ethic and intelligence.
To verify the students' reports, researchers checked the results against academic records and test scores.
The first-borns had higher test scores in math and verbal ability, while the later born children had better grade point averages in English and math.
In separate experiment, researchers asked 76 pairs of siblings in high school to rate themselves on a series of statements designed to assess personality. They found younger siblings to be more extroverted, sentimental and forgiving than their older counterparts. Older siblings tended to be perfectionists more.
"While parents might want to treat each child equally, it's almost impossible," Frank said at the Annual Convention of the American Psychological Association
Frank's study focused more on sibling relationships, which are usually overshadowed by more common studies of mother-child or father-child relationships.
Frank's team hypothesized that first-borns score higher on intelligence measure because at some point, they were the only recipient of their parents' attention.
Younger siblings receive mentoring from their older siblings and feel the need to be more competitive than their older counterparts, thus earning better grades. They are also more open to new experience because they've witnessed challenges their older siblings have overcome, thus giving them more security in overcoming obstacles.