and it's not just at Christmas time when we're

arguing over why the elder sibling has to peel potatoes

and why everyone's forgotten

the middle child has no gravy with their lunch.

Although you may not realise it,

you've probably absorbed these stereotypes from birth order theory.

Birth order theory is the idea that

our position in our family affects our personality characteristics,

our IQ, and even our life success and that these last long into adulthood.

Now at this point I should probably let you know

that I am the youngest of four, but I absolutely promise you

that that will not bias in any way whatsoever

the information I'm about to give you now.

One of the most influential characters in this story

was Alfred Adler - an Austrian physician and psychotherapist.

He wanted to try and understand why children

who were raised in the same family seem to have different personalities.

Now at this point I should mention that Alfred Adler

was actually a middle child - the second of seven children.

In 1927, Adler theorised that birth order affected personality hugely

because parents treated children differently

according to whether they were the eldest or the youngest.

He also believed that parents comparing siblings

created a sense of inferiority.

Since then, researchers have added to this list

of birth order characteristics.

Here are just some of them - they might ring a few bells.

For example, the older child -

thought to be a people pleaser, responsible, reliable, cautious

but perhaps bossy and controlling.

The older child traditionally

has been thought to be given a lot of parental attention

so when the second sibling arrives

they can often feel neglected or dethroned.

Famous older children include Winston Churchill and JK Rowling.

The middle child is thought to be often left out, ignored,

so they tend to be the peacemaker.

They tend to adapt their personality to fit in

with perhaps what the older child has already taken away

in that family niche.

Famous middle children include Bill Gates and Madonna.

The youngest child is often thought of as being self-centred, manipulative,

fun, entertaining and charming.

The youngest child is often thought

to have to work harder to get attention

and to maintain independence and seem different from their siblings.

Famous younger children include Cameron Diaz and Mahatma Gandhi.

And if you don't have siblings then don't feel left out

because Adler had something to say about the personality characteristics

of people without siblings.

Only children are often thought to be self-centred, independent,

looking for approval and mature.

As they have no older or younger siblings

they often take on the personality characteristics

of either the eldest child or the youngest child.

Famous only children include Daniel Radcliffe and Leonardo da Vinci.

In 1996, American psychologist Frank Sulloway

theorised that these differences may be due

to Darwin's theory of competition and survival.

Within every family, every child has to compete

for parental attention and investment in order to survive.

So for example, the elder sibling

taking on the responsible role of looking after the younger siblings

so when the younger child comes along

they have to develop a different way of being in that family

and find their own niche

for example, by being more adventurous.

By doing this they reduce competition

and enhance cooperation within the family -

so chances of survival for everyone are increased.

Over time, results of further studies have been inconsistent.

Some have totally backed up Adler's theory,

others have totally negated it.

Some studies have shown there are differences

but that these are not meaningful and others have shown that actually

any differences found are due to study design.

For example, how many siblings are in a family

or the relative ages of siblings.

So who knows?

Birth order is a fascinating subject

but pinning down exactly what impact it has, if any,

is still a massive challenge.

But from a personal perspective,

I still think the youngest child is by far superior.

Thanks for watching!

Don't forget to subscribe and click the bell to receive notifications for new videos.

See you again soon!