Researchers in Holland believe they may have worked out why it is that so many men grow ginger or red beards even though they don’t have red hair.

It is to do with a mutated gene as well as the fact that the genes that determine a man’s beard colour are not necessarily passed on from the same source as the genes that determine their hair colour.

A person’s genetic makeup doesn’t come just from their parents but also their grandparents and more distant ancestors.

It is likely that most men in Celtic countries such as Ireland will have red hair somewhere back in their family tree.

It means that the hair on a man’s head can be different from the hair on their face and body.

Petra Haak-Bloem works at Erfocentrum, which is the Dutch National Information Centre that keeps data on genetics and hereditary traits.

He told Vice magazine: “The genes that determine hair colour are so-called ‘incomplete dominant hereditary traits.’ This means that there isn’t one single gene that’s dominant over the rest, but all genes influence each other.

“Generally speaking, people inherit hair colour not only from their parents, but also from their grandparents and earlier ancestors. So it’s entirely possible that one distant ancestor had a hair colour that suddenly appears again though a certain combination of genes—and that can be quite unexpected for parents.”

The colour of a person’s hair depends on the amount of melanin, or pigment, in the hair. This is determined by DNA which encodes the kind of pigment and the amount of pigment a person has.

Haak-Bloem said: “For white people the shades are dependent on two sorts of melanin: eumelanine (black pigment) and pheomelanine (red pigment). Hair cells of dark haired people only contain eumelanine. Blondes have less eumelanine. And redheads’ hair contains mostly pheomelanine.

“More than a decade ago, researchers discovered that one gene (MC1R) on chromosome 16 plays an important part in giving people red hair. MC1R’s task is making a protein called melanocortin 1. That protein plays an important part in converting pheolmelanine into eumelanine.

“When someone inherits two mutated versions of the MC1R-gene (one from each parent), less pheomelanine is converted into eumelanine. The feomelanine accumulates in the pigment cells and the person ends up with red hair and fair skin.”

If a person has only one mutated MC1R gene it can result in red facial hair even if they brown or blond hair.