The mystery of orange hair is much more complicated than previously thought.
So far it has been thought that children have redheads, they need to inherit two copies of a gene called MC1R, one of the mother and one of the father.
MC1R is a recessive gene, i. it can not manifest itself in the presence of a dominant gene and only makes it when the person receives copies of his mother and fatherhood.
However, not all people who inherit the MC1R gene have orange hair, so scientists suggest that other factors play an important role.
What these factors were, was a mystery … so far.
A study by the University of Edinburgh in the UK has just shown why the MC1R gene only explains part of the puzzle.
The research, developed by the University of Edinburgh researchers, is more genetic research done to redhead so far,
Other researchers in Scotland have tried in the past to explain the keys to orange hair.
About 1 to 2 percent of the world's population is a redhead, but in Scotland, the percentage is close to 13 percent, equivalent to 650,000, according to ScotlandsDNA.
Scientists at the University of Edinburgh have studied DNA from nearly 350,000 people who participated in the British project called United Kingdom Bioban, which gathers information on the health and genome of more than 400,000 people in the UK.
When researchers compare the genome of redheads to those of brown or black hair, they find eight differences in hair color.
And they also found this some genes control when MC1R is expressed or not,
Orange hair is not just the result of a recessive gene, but rather of the complex interaction of at least eight genes,
Blonde and brown
Researchers have also found differences in almost 200 genes related to people with blonde or dark hair.
It has a color gradient that turns from black to dark brown, light brown and blond. And this gradient is due to the increasing number of variants of these 200 genes.
Something surprised scientists is that many of these genetic differences are not related to pigmentation, but to the texture of hair. Other variants determine how much hair grows, that is, whether straight or curly.
"Our work reveals most of the genetic variations that contribute to color differences in hair," he said. Albert Tennesa, a researcher at the Rosslyn Institute at the University of Edinburgh.
Ian Jackson, a genetic expert at the same center, said the work was an example of "the strength of UK Biobank, a unique genetic study in the UK that allowed us to make these findings."
The study was published in Nature Communications.