They're not 'dumb blondes' after all: Women with the natural hair colour are MORE intelligent than brunettes and redheads

The study found natural blondes had an average IQ score within 3 points of brunettes and redheads. Goldie Hawn (pictured) is a member of Mensa

Blondes may be 'bombshells' who have more fun, but they're also tarnished with a reputation for being dumb. 

Having a 'blonde moment' has even become a phrase used when someone makes a mistake.

Now, a study has found this stereotype is not only inaccurate, the opposite could actually be true. 

Researchers found women who said their natural hair colour was blonde had an average IQ score within 3 points of brunettes and those with red or black hair.

Data for the study came from the National Longitudinal Survey of Youth 1979 (NLSY79) - a national survey of people who were between 14 and 21 years old when they were first interviewed in 1979. 

In 1980, participants in the NLSY79 took the Armed Forces Qualification Test, or AFQT, which is used by the Pentagon to determine the intelligence of all recruits. 

The overall AFQT score is based on word knowledge, paragraph comprehension, math knowledge and arithmetic reasoning.

In 1985, all participants were asked, 'What is your natural hair colour?'

To eliminate any bias in the IQ tests caused by ethnic and racial differences, Jay Zagorsky from Ohio State University dropped all African Americans and Hispanics from the analysis, reducing the sample size to 10,878 white, females.

The findings showed that blonde-haired white women had an average IQ of 103.2, compared to 102.7 for those with brown hair, 101.2 for those with red hair and 100.5 for those with black hair.

Blonde women were slightly more likely to be in the highest IQ category than those with other hair colours, and slightly less likely to be in the lowest IQ category. 

The study can't say whether there are any genetic relationships between hair colour and intelligence, but Zagorsky did find one fact that could at least partially explain why blondes showed slightly higher intelligence - they grew up in homes with more reading material than did those with any other hair colour.

The findings showed that blonde-haired white women had an average IQ of 103.2, compared to 102.7 for those with brown hair, 101.2 for those with red hair and 100.5 for those with black hair. Marilyn Monroe (pictured left) was said to be a shrewd businesswoman. Baroness Michelle Mone (right) is an entrepreneur 

'If blondes have any slight advantage, it may simply be that they were more likely to grow up in homes with more intellectual stimulation,' he said.

Zagorsky noted that more women than expected in the NLSY79 reported that they were blonde. 

In the survey, 20.7 per cent of white women reported being blonde, compared to only 17.1 per cent of men. 

Assuming hair colour is not related to gender and that men were less likely to colour their hair, Zagorsky said the results suggest that about 3.5 per cent of women reported their natural hair colour as blonde when it was not.

Zagorsky said he couldn't say for sure how that may have affected the results, but he said the major finding was almost certainly still true -blondes could hold their own intellectually with those of any other hair colour.

While jokes about blondes may seem harmless to some, it can have real-world implications, said

'Research shows that stereotypes often have an impact on hiring, promotions and other social experiences,' Zagorsky added.

'This study provides compelling evidence that there shouldn't be any discrimination against blondes based on their intelligence.'

'I don't think you can say with certainty that blondes are smarter than others, but you can definitely say they are not any dumber.'

The results for blonde white men were similar - they also had IQs roughly equal to men with other hair colours.

The study was published in the journal Economics Bulletin.