Family stereotypes may be accurate, says study; the battle over the psychology of birth

No doubt you've heard the family stereotypes, middle one is difficult, the eldest is bossy, while the youngest is spoiled. Funny thing is that according to a recent peer-reviewed published study from the University of Oslo, the stereotypes are in fact pretty accurate.

The scientists have found that eldest siblings are, on average, significantly "more intelligent" than second-borns. It may not seem like much, but 2.3 points on the IQ scale – the average difference between first and second siblings – could be enough to determine whether or not someone gets into a good college.

But don't expect this study to quell the debate over whether or not anything meaningful can be deduced from looking at one's order of birth. In one meta-analysis of 1,000 studies on the topic, the conclusion was that "the data on birth order was so flimsy and contradictory that many of the conclusions were not worth a candle."

For every study that notes a meaningful difference in birth order there will be critics with charges of bad science. That's one of the things that is unique about the University of Oslo study, it was published in the prestigious he peer-review journal "Science."

Once you get over whether or not the differences are meaningful the debate moves to possible reasons for such differences. Specifically whether it is nature (that is something that happens in the womb) or nurture (that is differences in the way that later children are reared).

Biology certainly seems to play a role in at least some aspects of birth order differentials as evidenced by the fact that birth order has been demonstrated to affect both height and sexual orientation.

On the nurture side of the argument, one study found that it was the actual role of being the eldest that was important. What mattered was having the the senior social rank within the family and performing the role of the eldest child and not born the eldest. Another one of the myriad of factors that has been cited in the debates is the fact that older siblings may act as a sort of "unpaid tutor" for later children which improves their verbal and cognitive skills.

So where does this leave us? The birth order theories might help you understand about some of the traits of your own brothers and sisters or perhaps how your own children are developing. However beyond that the applicability of the theories, even if true, appears to be rather limited. It is doubtful that you would want to base an important decision (say hiring or dating) based on birth order.

h/t: Truemors