Yet there is a long tradition of respectable science in this field.It began in 1874 with Sir Francis Galton, a cousin of Darwin and father of the eugenics movement, which did not then have the taint of disfigured ideology it picked up in the 1930s."This study provides evidence that the relation between birth order and IQ scores is dependent on the social rank in the family and not birth order as such," Kristensen explains.
Certainly, you could argue, the risk-taking, revolutionary characteristics ascribed to last-borns are the chief traits of Charles Darwin, Copernicus, Descartes, Mozart... Try to predict the birth order of those people mentioned above without first being told (admittedly difficult with the heir to the throne), and few people would get it right.
After knowing their birth order, we find it quite easy to fit them into the appropriate personality pigeonhole – rather like reading a horoscope and finding that it neatly explains elements of your current situation.
What he found was pretty convincing evidence that it was not the fact of being born first that gave you an intellectual head-start in life; it was the actual role of being the eldest that was important.
It was being reared as the eldest, rather than being born the eldest, that mattered.
Using the IQ tests taken from the military records of 241,310 Norwegian conscripts, 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.
A proud brother or sister who shoulders responsibility – with or without encouragement?
What if I were to ask you which member of your family is the most extroverted, or the naughtiest? Does the thought of a middle child conjure pictures of a tortured soul, forever torn between two extremes?
Professor Frank Sulloway, who has become a leading proponent of the birth-order idea, has gone as far as to suggest that the Norwegian study dispels any previous doubts about the intellectual prowess of first-borns.
Sulloway, of the University of California, Berkeley, says that any major criticisms of the birth-order idea – that the personality differences between families are so great that they obscure any differences within the families – can now be laid to rest.
But can biology and birth order within the womb explain these IQ differences, or is it down to upbringing within the family?