Toronto (eCanadaNow) - Older siblings score higher on IQ tests than their younger brothers or sisters, according to a new study.
Norwegian researchers found that it does not matter if the child is the first born or an only child, but rather that they are the senior child, that seems to effect IQ scores.
It‘s a matter of what they call social rank in the family — the highest scores were racked by the senior child — the first born or, if the first born had died in infancy, the next oldest.
"This study really puts to an end a debate that's been going on for more than 70 years," said Frank J. Sulloway, a visiting scholar at the University of California, Berkeley, Institute of Personality and Social Research, and the author of an accompanying commentary in the journal. "The theory of biological differences is pretty much dead as a doornail."
Researchers foundt that the average IQ of first born men was 103.2.
And for third-borns, the average was 100.0. But if both older siblings died young, the third-born score rose to 102.6.
"This IQ difference has impact on educational potential on the population, giving first-born an advantage over later-born," he Sulloway. "However, on the individual level, this effect is so small that it gives little predictive power."
The Norwegian scientists collected IQ data on a quarter- million people 19 years old and younger, in the largest study ever to compare the intellect of children within families.
IQ, or intelligence quotients, are based on tests to measure intellect.
The findings were published in this week's issue of Science
