An Adelphi University student's research that found firstborns score higher on intelligence while younger siblings often get better grades drew some attention at a national psychologists' convention in San Diego this week. But for the researcher, Tiffany Frank, 26, it was personal.
"My interest in this started because I have an older sister who's very smart," she said of elder sister Samara, the firstborn. "I felt no matter how hard I worked, I wasn't as smart as her," said Frank, the youngest of three, who is pursing a doctorate in psychology at Adelphi.
Frank spoke by phone Friday from San Diego, where she delivered her paper at the annual convention of the American Psychological Association.
Her research on 90 pairs of siblings at Lawrence High School on Long Island found that while the firstborn scored highest on the national Iowa Test of Basic Skills, suggesting a higher level of aptitude, younger siblings had higher grade-point averages.
Frank, who lives in Queens, began the study eight years ago, while a junior at the high school. She was a semifinalist for the research in the 2002 Intel science competition. That research formed the basis of her current study.
"We were really surprised that the firstborn came out with higher intelligence, but the later-born worked harder and had higher GPAs," Frank said. "You would think the firstborn would have higher grades."
Her study differs from some of the myriad birth-order literature in its methodology, which focuses on the intelligence, achievement and personality of a sibling within families. Other studies have looked at unrelated random people and focused on their achievements based on their birth order, she said.
The second part of the study, conducted by Frank's young co-author Hannah Turenshine, focused on sibling personalities, concluding that younger siblings were more extroverted than the firstborn, a finding at odds with some previous research. Turenshine, 18, of North Woodmere, N.Y., said that difference could be the result of differing definitions of "extrovert."
The 76 different pairs of siblings were each given surveys to assess their own personalities. Resulting comparisons showed younger siblings were "more sincere, more emotional, more sentimental, more socially bold," said Turenshine, who graduated from Lawrence High this year and is headed to Binghamton University in the fall. Firstborns tended "to have stronger perfectionist tendencies, and were "more fair."
Explore further: Ketamine shows significant therapeutic benefit in people with treatment-resistant depression