Stoking the fires of sibling rivalry doesn't take much, but the results of the biggest study in history into birth order and personality won't do anything to help matters, revealing as it does that first-born children have a higher IQ than those born later. Ouch.
Researchers at the University of Illinois used a sample of 377,000 schoolchildren and found there were also differences in personality traits, with the eldest sibling tending to be more extroverted, agreeable and conscientious.
Which sounds like bad news for those of us born second or third, but before you use it to shore up your middle child syndrome, bear in mind the IQ difference is only one point - and Dr Rodica Damian, postdoctoral researcher and professor of psychology at the University of Houston, described it as "statistically significant but meaningless".
Though the research also found such differences as first-born children being less likely to have anxiety than their siblings, Dr Rodica said they were "infinitesimally small" and parents shouldn't worry too much.
She explained: "The message of this study is that birth order probably should not influence your parenting, because it’s not meaningfully related to your kid’s personality or IQ."
Professor Brent Roberts, who led the huge study alongside Dr Rodica, added that while consistent results could sometimes be significant, it was unlikely families would be able to spot these particular findings in their own children.
He said: "In some cases, if a drug saves 10 out of 10,000 lives, for example, small effects can be profound. But in terms of personality traits and how you rate them, a 0.02 correlation doesn’t get you anything of note [...] You’re not going to be able to sit two people down next to each other and see the differences between them."
So you can down your arms, because all is calm on the sibling front. Even though everyone knows firsts get all the fun, lasts get all the freedom and middles get the raw deal. Right?
Images: Rex Features