You may have heard that the second brother is a little… slow, but a recent study will prove hearsay wrong birth-order is irrelevant to IQ and to personality. Although many a doctor struggled to find evidence of the contrary, it seems that there is literally no truth behind this statement.
The study was made on a very large group of 377,000 students of high-school and uncovered some interesting results. Compared to their younger brothers or sisters, the older ones have a higher average IQ. This could prove statistically relevant, yet not at all scientifically relevant.
The difference in average IQ was 1 point. Older siblings were just one point IQ smarter than younger ones. These were the findings of the University of Illinois study, led by Prof. Brent Roberts. These findings confirm, from a statistical point of view, previous studies which were a bit biased towards these results. However, the data this one provides is irrelevant to the whole picture, as it brings the contradiction that older and younger brothers and sisters, however slightly different in IQ, are still insignificantly different.
The study also looked at the personalities of the siblings, so as to test the theory that the oldest child is a natural born-leader, the middle child a more laid-back and easy going version of the first, and the last one, the rebel one, the prodigal son (or daughter). However, the belief, which is part of common belief, and probably has its origins in Bible studies, has no real life proof.
The test has shown that personality differences are not inherent and do not pertain to the genetic manufacture of each of the siblings. Yet, these differences, Roberts says, are more likely to be impeded upon the child due to different parenting strategies that develop as the parents themselves increase in age (and wisdom, some may argue). The study itself found that the concrete personality differences are inconclusive.
Roberts firmly believes that the results of his study are a breakthrough in psychology studies, and the biggest ever of those which have looked at personality and birth order differences. Thera had been another previous major study concluded by Alfred Adler at the beginning of the 20th century. The major flaw of that one, which had results completely opposite to this one and which introduced science in support of the different siblings idea, was that the test group was relatively small, and only included members of the same family.
Image source: conversationswithmymother.com