A 'curly hair gene' has been discovered by scientists at the Queensland Institute of Medical Research (QIMR), paving the way for advances in hair treatments and forensic science.

The study, published in the American Journal of Human Genetics, found the genetic variations responsible for curly hair in those of European descent. Previous research has suggested that around 45 per cent of European people have straight hair, 40 per cent have wavy hair and 15 per cent have curly hair. It has also been found that the chances of inheriting curly hair is as high as 90 per cent.

The scientists, at the QIMR Genetic Epidemiology Laboratory, conducted a genome-wide association scan for hair morphology (straight, wavy or curly), which involved analysing data from 5,000 twins in Australia over a 30 year period. The researchers compared the genome maps of the twins and found the same genetic variations existed for both curly and straight hair.

A variation in the Trichohyalin (TCHH) gene is thought to make a change in an amino acid which determines the straightness or curliness of the hair. While the gene has been understood to have a role in the development of hair follicles for some time, its direct link to determine curly or straight hair has only just been found out. Professor Nick Martin, who led the study, said: 'This gene has been known for well over twenty years as being involved in hair production and it's a gene that sits in the sheath that's around hair roots.'

The scientists are now working on treatments to make straightening curly hair easier, including a way to develop a pill for this: 'Potentially we can now develop new treatments to make hair curlier or straight, rather than treating hair directly,' Professor Nick Martin told the Daily Telegraph newspaper. He added: 'That is one angle we will be working on and which I will be discussing with a major cosmetic company in Paris in January.'

The discovery may also be able to help with police investigations. 'The most immediate application is likely to be in forensics,' said Professor Martin, adding: 'We might be able to refine indentikit pictures from DNA samples left at a crime scene to say whether the suspect had straight or curly hair. We can already predict their hair and eye and skin colour, so this would be another trait to refine the picture.' Predictive tests will also be developed : 'We could certainly predict whether it was more probable that a baby would have curly or straight hair. We plan to keep working on this to improve the prediction', he said.