It is much more complex than previously believed. The genetic enigma of redheads was a scientific mystery. It was believed that the cause for this peculiarity was known. The person had to inherit two copies of a gene called MC1R, one from the mother and one from the father. But an investigation reveals the truth behind it.
MC1R is a recessive gene. It cannot manifest itself in the presence of a dominant gene. It only does so when the person receives the maternal and paternal copies. But not all people who inherit the MC1R gene have orange hair. There had to be other factors. Which is it?
Genes
A study from the University of Edinburgh in the United Kingdom says so. It is the largest genetic research carried out on redheads to date. About 1 to 2% of the world's population is redhead. But in Scotland the percentage is close to 13%, which is equivalent to 650,000 people.
Scientists at the University of Edinburgh examined the DNA of almost 350,000 people. They participated in the British project called UK Biobank. It brings together information on the health and genome of more than 400,000 people in the United Kingdom. The researchers compared the genome of redheads with that of people with brown or black hair. And they found eight differences linked to hair color. They also found that some genes control whether MC1R is expressed or not.
Orange hair is therefore not simply the result of a recessive gene. It comes from the complex interaction of at least eight genes. There were differences in almost 200 genes associated with people with blonde or dark hair. There is a color gradient that goes from black, to dark brown, light brown and blonde. And that gradient is caused by an increasing number of variants in those 200 genes. Many of these genetic differences are associated not with pigmentation, but with hair texture. Other variants determine how the hair grows, that is, whether it is straight or curly.
Solved puzzles
“Our work unravels most of the genetic enigma of redheads.” This was pointed out by Albert Tenesa, one of the researchers. Ian Jackson, a genetics expert at the same center, said the work is an example of the “power of UK Biobank, a unique genetic study in the United Kingdom that allowed us to make these discoveries.”
