According to a large study, the oldest children in families tend to develop higher IQ's than their siblings.
These findings could settle more than fifty years of scientific debate about the relationship between IQ and birth order.
There was, on average, a three point difference in IQ between the oldest child and the next closest sibling, a slight but significant difference.
The results made it clear that the difference was a result of family dynamics, rather than biological factors; children who became the oldest child after the early death of a sibling had the same scores, on average, as biological firstborns.
The study looked at the birth order and IQ scores of more than 240,000 men aged 18 or 19, based on their military records.
After correcting for factors that can affect scores, such as parents' education level, researchers found that the oldest children scored an average of 103.2, whereas second children averaged 100.3 and thirdborn children averaged 99. The scientists then looked at the IQ scores of more than 60,000 pairs of brothers, and found the same results.
The New York Times June 21, 2007
Dr. Mercola's Comment:
The 3 or 4 point advantage the oldest children get on IQ tests may not sound like much, but even such a small difference can be the tipping point for many -- allowing the older children to get into better schools, for example.
But what causes this slight jump in IQ?
There are several theories, including the idea that firstborns have their parents' undivided attention as infants. In theory this would account for their enriched vocabulary and reasoning abilities. Another possibility is that older siblings consolidate and organize their knowledge while performing their natural role as tutors to their younger brothers and sisters. A third possibility is that siblings tend to develop different sets of qualities in order to find their "niche" within the family, without competing over the same skill. For example, whereas firstborns nab the high-IQ trophy, younger siblings tend to live more adventurous lives and their accomplishments tend to be of the less conventional kind.
That last theory brings home an important point; an IQ score is not the be-all and end-all of human existence, and people can develop many different skills in many different fields.
This study has some personal relevance for me as I am the oldest of five children, and although we've never compared IQ scores, I am the only one to have completed a doctorate degree, but more importantly, seem to have the strongest passion for learning. I have distinct memories of my mother helping me read at a very early age and encouraging me along.
This would certainly tend to support the theory postulated by the researchers and tends to make lots of sense. The fascination of having a child tends to wear off by the time number two runs around which could result in less attention and a decreased IQ.
By the way, if you want to ensure that all of your children have the highest IQ they can have, make sure that your babies are breastfed for as long as possible. Without question, this is the single most important thing that can be done. And, while relative IQ may not be everything, it is true that a higher IQ is linked to a longer life, so all of your children will benefit from this.
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