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The Genetic Explanation for Blond Hair

blond hairThey say that blonds have more fun. You might belong to a family where everyone has blond hair. Or, maybe your family tree includes people with blond hair and also people with a variety of other hair colors. Genealogists may wonder why some members of their family ended up with blond hair while others had dark hair. Scientists have discovered that there is a genetic explanation for this situation.

We associate blond hair with youth. That may be due to the number of babies that start out as blonds. Many grow up to become adults with darker hair. We also associate blond hair with sexiness. Marilyn Monroe wasn’t a natural blond. She had brown hair. She became famous after dying her hair blond.

If you do not happen to be a blond, and wish to become one, you can follow in Marilyn’s footsteps and dye (or bleach) your hair. Eventually, your hair will grow to reveal roots that are your natural hair color. There are those who lament that they were not born with blond hair.

Scientists have been investigating the genetics behind blond hair. They found that replacing one of DNA’s four letters at a key spot in the genome shifts a particular gene’s activity and leads to fairer hair. This is a short explanation for what happens in our genes that cause a person to have blond hair (or to have darker hair).

An article in Science, written by Elizabeth Pennisi, was titled “The Genetics of Blond Hair.” It provides a longer, more detailed, explanation of what I have briefly touched on here. In a small portion of her article, she explains:

Over the past 6 years, studies of genetic variation in thousands of people have linked at least eight DNA regions to blondness based on the fact that a certain DNA letter, or base, was found in people with that hair color but not in people with other hair colors. Some of those base changes, or single-nucleotide polymorphisms (SNPs), were in genes involved in the production of pigments, such as melanin. Mutations in these genes typically change skin and hair color.

She goes on to explain that SNPs that lay outside genes, but that could be part of the regulatory DNA, could also result in a change to a person’s hair color (but not skin color) or vice versa. This is because regulatory DNA can change gene activity in just certain areas of the body.

One very interesting thing about these discoveries is that it demonstrates how changes in segments of DNA that control genes are important to what an organism looks like. In other words, it shows that genes can cause changes – and that small portions of a particular gene can also cause changes. It also makes it clear, to the dismay of some, that the scientists have not discovered a way to permanently change a person’s hair from brown to blond.

Image by Chun Kit To on Flickr.

Related Articles:

European Blonds

Physical Characteristics of an Ancestor

How Much Do You Know About Your Genes?

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