Professor James McInerney, visiting the National University of Ireland, Maynooth, from Harvard, has posted a map showing the distribution of red hair in Europe online.

A professor of biology, McInerney points out the high frequency of red hair “in Ireland, Scotland and Wales with another large patch of high-frequency phenotypes in Russia.”

Recent studies have found that 10 percent of Irish people boast of red hair while 13 percent of our Celtic cousins, the Scottish, are redheads.

On the site, where he posts “science-based curiosities,” McInerney writes that this kind of genetic data can answer questions such as whether redheads were “more widely distributed throughout Europe in the past and nowadays [are] only found on the periphery because of a later take-over of Europe by people that didn’t have red hair or alternatively, red hair might have originated in those places where it is found now and it never had a wide distribution.”

He explains the science behind what turns hair red. McInerney said, “Red hair occurs when an individual has two recessive alleles for the Melanocortin 1 Receptor....The gene for this protein is found on chromosome 16.”

He continued, “If you have the recessive alleles, then you produce phaeomelanin (a yellow-ish reddish skin and hair pigment) and not eumelanin (the brown-black pigment).  If you have one recessive allele and one dominant allele, then you won’t have red hair and if you have two dominant alleles you won’t have red hair.”

Many theories about what makes a redhead exist including that of recent research carried out in by the ScotlandsDNA project which theorizes that having red hair and fair skin is a deliberate genetic adaptation, meaning it helps to take advantage of sunny days and allows the body to absorb more vitamin D.

Managing director of the ScotlandsDNA project, Alistair Moffat said, “I think it’s to do with sunshine. We all need Vitamin D from sunshine but Scotland is cloudy.

“We have an Atlantic climate and we need light skin to get as much vitamin D from the sun as possible.”

Mind you this would also explain why there are so many Russian red heads!

Map created by Harvard professor James McInerney shows how red heads are spread around