From 27 to 29 August redheads from around the world will be gathering again in Tilburg for Redhead Days, an annual international event that celebrates red hair. But where does red hair actually come from? Why is it relatively uncommon to have red hair? And can you pass red hair on to your children even if you do not have red hair yourself? You will find all the answers in this article.
Where does red hair come from?
It is estimated that the most significant genetic mutations that lead to red hair colour (in Europe) are between 30,000 and 80,000 years old. We see these mutations the most in countries where pale skin is more common and where there is less sunlight. Take Scotland and Ireland, for example, where around 12% of the population have red hair. By way of comparison, roughly 3% of the Dutch population are redheads.
There are theories that the pale skin with which red hair is often paired was favourable from an evolutionary point of view in less sunny areas. This is because pale skin still produces sufficient vitamin D when there is little sunlight. In sunnier countries pale skin (and red hair with it) is less favourable, as pale skin increases the risk of sunburn.
Red hair and melanin
The colour of our hair is determined by the substance melanin, which our body produces in two variants: eumelanin and pheomelanin. The ratio between these two variants determines whether you have a pale skin colour, whether you are sensitive to the sun and your predisposition to freckles, as well as the colour of your hair. To be precise, people with red hair have little eumelanin and a lot of pheomelanin (eumelanin is responsible for a darker colour, while pheomelanin colours the hair red).
Red hair and heredity
The gene that plays the biggest role in whether a person inherits red hair is the melanocortin 1 receptor gene, better known as MC1R. In most people, MC1R stimulates the production of eumelanin, but mutations in the gene can cause this production to be reduced. Instead, more pheomelanin is produced.
There are more than seventy known variants of the MC1R gene that can influence your hair colour. You inherit most of these variants recessively. This means that you will only get a red hair colour if two ‘alleles’ of the gene are present that suppress eumelanin production. It is therefore possible for two people, neither of whom has red hair but who both carry this gene, to unexpectedly have a child with red hair.
With some variants of the gene, red hair can also occur if you have just one ‘allele’ of this gene. This is the case for approximately 10 to 20% of people with red hair. They also have hair that is a different shade of red. In addition, there appears to be evidence to suggest that a single variant of the gene can influence the likelihood of a red beard in men, as well as your skin type and your chance of having freckles.
How do I know if I can pass on red hair to my children?
You can, of course, see whether there is anyone with red hair in your family. However, even if this has not been the case for generations, it is still possible that you carry a (recessively inherited) red-hair gene. To find out whether you have such a variant of the MC1R gene, you can take a DNA test.
If you opt for an iGene DNA test, this will not only tell you how likely it is that you will have red hair, but will also inform you about all kinds of other hereditary traits.
Flanagan, Niamh, et al. "Pleiotropic effects of the melanocortin 1 receptor (MC1R) gene on human pigmentation." Human molecular genetics 9.17 (2000): 2531-2537.
Harding, Rosalind M., et al. "Evidence for variable selective pressures at MC1R." The American Journal of Human Genetics66.4 (2000): 1351-1361.
Rees, Jonathan L. "Genetics of hair and skin color." Annual review of genetics 37.1 (2003): 67-90.