Did anyone really think there was serious proof that all those blonde jokes were true? Probably not.
Then last year, scientists confirmed it: our hair colour is completely unrelated to our personality and intelligence.
So while we can now say definitively the genetic mechanism that controls blonde hair, for instance, doesn’t alter the biology of any other part of the body or brain, it still won’t stop us making assumptions based purely on hair colour.
And quite rightly so.
Because while it’s true the colour of hair we’re born with doesn’t dictate how bright, flighty or flirty we are, the colour we choose to be speaks volumes about how we’d like to be seen.
We know if we’ve got dark hair, we’ll be seen as more serious than someone who’s blonde, who’ll score high on sex appeal but not so great on intelligence or friendliness.
If every redhead got a dollar each time someone blamed an emotional outburst on their hair colour, most could retire by 40.
Every time we reach for a bottle of hair dye or instruct our hairdresser to add streaks of sunshine or warm, winter lights, we’re effectively tweaking our personality.
Our hair colour changes how others see us and treat us - and how we feel about ourselves.
When Times columnist and brunette Caitlin Moran pulled on a peroxide white wig for a fashion shoot, she said she not only felt ‘dangerously splendid’ she “could already see that being blonde would change my life: that my hair would want to take me out to places and be noticed.”
Hair colour isn’t like inheriting Mum’s large hips or short legs.
We don’t have to shrug, say, ‘Oh well, mousy brown it is’ because there is something you can do about it.
Most women don’t accept what Mother Nature doled out (how many women over 21 do you know with ‘virgin hair’ - hair that’s never been coloured or highlighted?)
If you’ve ever doubted how much hairstyle and colour influences personality, think back to the last ‘fancy dress’ party you went to.
You’re guaranteed good gossip the next day because people behave out of character.
When we change our hair colour, we take on the personality stereotype that goes with it.
If you’re shy or lacking in confidence, a switch from brunette to blonde could be just what you need to practice being a new, more adventurous you.
Dramatic colour change is also fabulous for forcing people to look at you afresh.
Fear you’re not being taken seriously at work? Turn up as a brunette with a smart new suit on, and things might change.
Want a jaded husband to see you anew or to turn a friend into a lover? Head for the hairdresser.
There might be not a scrap of evidence to support the hair colour stereotypes but we’ll all continue to use it to our advantage anyway!