Because now scientists have found that the eldest child is also more likely to have a higher IQ.
According to researchers from The Leipzig University in Germany, this is down the NURTURE not nature, and comes about due to two factors.
Number one - the eldest child has their parents undivided attention - at least for the first few months.
And two - as the eldest child, they are expected to teach their younger siblings how to do certain things, which helps them develop the brain further.
But before you middle and younger siblings panic, the difference in IQ is relatively minimal, with scientists estimating it drops 1.5 IQ points per sibling.
The effect is also seen far stronger the larger the family, with two children families seeing little difference.
Another interesting observation from the study was that eldest children tended to KNOW they were smart, whereas younger siblings often doubted their intellect (time to stop boasting, oldies!).
