Red Hair Gene: The Basics
The red hair gene is probably one of the most intriguing of human traits.
Hair color is an inherited feature determined by the gene copies a child gets from both parents.
About 90% of the global population have dark hair, with just a few exceptions.
Globally, 1-2% of the population has red hair, which is considered rare.
Why Do Some People Have Red Hair?
Melanin, a coloring pigment produced by the melanocyte cells in the hair, determines hair color.
When melanocytes produce an excess of eumelanin, a type of dark-colored melanin pigment, people get black or brown hair.
Those who don’t produce enough of this pigment have blond hair.
The melanocytes in individuals with red hair produce another type of pigment called pheomelanin.
Pheomelanin is a yellow/reddish pigment that causes the iconic red-colored hair.
The type of melanin pigment produced by the melanocyte cells is dependent on a person’s genes.
Image: Types of Melanin Pigments
MC1R Gene, Melanin Pigments, and Red Hair
MC1R gene is one of the strongest influencers of red-colored hair.
This is also called the red hair gene.
It provides instructions for producing the melanocortin 1 receptor.
This receptor decides which type of melanin the melanocytes produce.
When the receptor is active, it encourages the melanocytes to produce eumelanin, leading to darker hair color.
When the receptor is blocked or inactive, more pheomelanin is produced, leading to reddish hair color.
Certain changes in the MC1R gene block the functioning of the MC1R receptor and encourages the melanocyte cells to produce pheomelanin instead of eumelanin.
This causes red hair in some individuals.
How Do You Inherit The Red Hair Gene?
Red hair is a recessive genetic trait.
This means that a person must inherit the genetic change associated with red-colored hair from both parents for it to be activated.
Many people may be carriers of one copy of the mutated gene but could still have darker hair color.
A study says that up to 40% of people in Scotland carry at least one copy of the mutated gene, but only 13% of them are redheads.
How Likely Am I to Have a Child With Red Hair?
The following scenarios will help understand a person’s likelihood of having a child with red hair.
Scenario 1: Both parents with brown hair + none of them are carriers of the red hair gene
In this case, there is an almost 0% chance that your child will be red-haired.
Scenario 2: Both parents with brown hair + both of them are carriers of the red hair gene
In this case, there is a 25% chance that the child will have red hair and a 50% chance that the child may have brown hair but carry the red gene.
Scenario 3: One parent with brown hair + one parent with red hair + brown-haired parent is not a carrier of the red hair gene
In this case, the child may carry the red hair gene but will not have red hair.
Scenario 4: One parent with brown hair + one parent with red hair + brown-haired parent is a carrier of the red hair gene
In this case, there is a 50% chance the child will be red-haired and another 50% chance that the child will be brown-haired and a carrier of the red hair gene.
Scenario 5: Both parents have red hair
In this case, all children will have red hair too.
How To Know If You Carry The Red Hair Gene
In some families, the past generations could have just been carriers of the red hair gene, and suddenly a child could turn up with bright red hair.
This interesting turn of events can be predicted by genetic testing.
Genetic testing can help identify if the parents are carriers of the MC1R gene and predict whether a child will have red hair.
Apart from aesthetics, studies report that red-haired individuals could be at a higher risk for developing certain conditions like skin cancer and increased pain sensation.
It may be beneficial to test whether or not a couple’s child would inherit red hair using genetic testing.
Summary
- Hair color is inherited from the parents, and only 1-2% of the world's population have red hair.
- Red hair results from the production of a reddish/yellow pigment called pheomelanin by the melanocytes of the hair cells.
- The MC1R gene is responsible for deciding hair color by controlling the functioning of the Melanocortin 1 Receptor.
- Mutations in the MC1R gene lead to an inactive Melanocortin 1 Receptor. This produces pheomelanin pigments, causing red hair.
- Red hair is a recessive genetic trait, meaning a person must inherit the abnormal gene variant from both parents for it to activate.
- Genetic testing may now help predict a child’s chances of inheriting red hair from the parents.
References
- https://www.livescience.com/26633-redhead-dna-gene.html
- https://www.thetech.org/ask-a-geneticist/what-are-my-chances-having-red-haired-child
- https://www.eupedia.com/genetics/origins_of_red_hair.shtml
- https://www.healthline.com/health/red-hair-blue-eyes
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5958947/
