Is the eldest child really the smartest? Sibling facts backed up by science

The relationship between siblings can be a love-hate rollercoaster with no brakes. Hair is pulled, names are called, battles are waged, and parents are tested – to the limit. But the tumultuous nature of sibling relationships isn’t the only fascinating thing about them. Through studies and on-going research, scientists have divulged numerous other quirks and patterns that occur within sibling relationships, some of which have a hefty impact on the way we turn out.

Take a look at some of our favourites – how do they stack up in your home?

1. Younger siblings have better social skills, but also tend to be more rebellious

Younger siblings learn a lot from their older siblings, the least of which is how to climb up a door frame in true Spidey form. In a study, the youngest were found to develop better social skills faster, be better sharers and more understanding that their older sibs were at the same age. On the flip side, the younger ones are a tad more cheeky than their older counterparts, exhibiting more rebellious and extroverted behaviour – no doubt because they have had to stand up to big brothers and sisters, and make their little selves heard. Cue mighty stance and furrowed toddler brow.

2. Siblings fight a lot, and it’s actually important that they do

It has been documented that siblings between the ages of three and seven years bicker, nitpick and (sometimes) throw things at each other around three-and-a-half times per hour. In younger siblings, you might see fights escalate to one every ten minutes (particularly when the TV remote in is play). But while parents might think their kids hate each other, according to experts, a good ratio of play to fighting is normal and healthy, provided the play time outweighs the fight time. By fighting, kids learn about compromise, conflict resolution and how to manage their emotions.

3. The eldest child is likely to be more intelligent

As if it’s not enough that the first born doesn’t have to live in hand-me-downs, or share mum and dad for a while, studies show the eldest child also gets a bigger share of brainpower than their little brothers or sisters. According to research, the eldest child in the family is likely to outperform their younger siblings, and has an average three-point IQ advantage.

4. The youngest sibling is often less prone to some allergies

A Japanese study suggests this is especially true when it comes to food allergies, hay fever and allergic conjunctivitis. But why this misfortune for the later born kids? Scientists point to the prenatal stage, suggesting that multiple births can build a stronger immune system in the womb, possibly explaining why subsequent children are less likely to develop these specific allergies.

5. The youngest child in large families tends to be shorter than average

Not just because they’re the youngest either. In a family study it was found that children with four or more older siblings had a lower birth length and a reduced rate of growth per year than other children their age. In the study, the overall height deficit in the youngest child averaged three centimetres by the age of ten.

6. Kids spend more time with their siblings than anyone else. (Even themselves!)

This. Despite the wars. In fact, it’s been reported here that by the age of 11, up to 33 per cent of a child’s spare time is spent with siblings – that’s more than with parents, carers, mates or teachers. So, while the battles are numerous and the noise in the house unbearable, the fact that siblings spend so much time together points to just how important the relationship is, and the many ways in which it shapes who kids become.

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