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Most Common Dominant Genes In Humans 

When looking at the most common dominant genes in humans, the physical makeup of a person can often be predicted.

By Alicia SpringerPublished 6 years ago 7 min read
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Photo by Vanessa Bumbeers

Some of the most common dominant genes in humans come from parental inherited gene variations known as alleles. Some are dominant and others are recessive, and prevalence is often awarded to the dominant gene, resulting in many easily definable and rather common physical traits among human beings. While parental inherited genes usually consist of two separate alleles, they also come in many different variations. Therefore, while of the many traits that each individual inherits from their parents are completely left to chance, others are easily predictable.

When dealing with common dominant genes among humans, the physical makeup of a person can often be predicted.

Right-Handedness

Photo by Averie Woodard

According to statistics, roughly 85 to 90 percent of individuals are right handed. While this is shown physically in early childhood, hand preference is actually developed before birth due to dominant genes.

In addition to presenting itself in almost 90 percent of the human race, right handedness arises during the right-left asymmetry developmental process which helps differentiate between the right and left brain hemispheres.

According to the Live Science website, handedness also provides an almost direct outward reflection of a human’s motor coordination and brain wiring. This means that by the genes affecting the body’s organ based symmetry in the way that they do, the dominant brain hemisphere and motor coordination of each person is also determined. Researchers have found that the dominant gene known as PCSK6 creates right sided parts, while the others decide how the body’s organs are oriented. In addition to PCSK6, researchers identified multiple other genes associated with hand dominance.

In rare cases, researchers also found that some humans with defective dominant genes have what is known as “handed isomerism.” This not only results in two left sided mentalities operating at the same time, but also accounts for multiple spleens within the body.

Dark Hair 

Photo by Yaoqi LAI

Resulting from hair follicle pigmentation, dark hair is genetically dominant. While it is shown in more than 50 percent of humans throughout the United States, almost 100 percent of people have dark hair in certain races. Due to Black, Latino and Asian gene pools, dark hair has remained an incredibly dominant gene, resulting in an almost 2:1 ratio worldwide.

While dark hair color is an obvious indication of the melanin levels of each human being, it also shows how many hair follicles are located throughout the scalp. Generally, the more scalp-based hair follicles someone has, the darker their hair color is.

Brown Eyes

Photo by Vanessa Bumbeers

Occurring in more than half of the world’s population (nearly 60 percent), brown eyes serve as one of the most common dominant genes in humans and are incredibly prominent over all other colors. While many children are born (initially) with blue eyes, pigment darkening often occurs, causing the eyes to turn brown. Consisting of pigments throughout the iris, pupil size often changes in size due to certain emotions. In addition to emotion based pupil changes, iris contractions and pupil size changes can occur when trying to see in the dark or focus on a certain object. When these emotions are heightened, it can also cause a change in color. Though these changes are often subtle, they occur a lot (especially in the first three years after birth).

Free Earlobe 

Photo by Daniela Avila

While some earlobes are directly attached to the side of the head, the genes that make up free swinging earlobes are often dominant. According to recent studies done by the Tech Museum Of Innovation, researchers found that unattached earlobes were dominant by simply observing the makeup of two separate families. In these studies, scientists noticed that while all earlobes were attached among the first family, everyones in the second were unattached. However, upon the marriage of a man from the first family and a woman from the second, all of the children’s were free swinging. This helped to determine that earlobe detachment was not only one of the most common dominant genes in humans, but also one of the most obvious.

Dimples

Photo by Allef Vinicius

In addition to being highly sought after by many females all over the world, small and subtle cheek indentions known as “dimples” are one of the most common dominant genes in humans. However, while individuals with these small and subtle indentions clearly express the dominant gene, it is not always guaranteed that their children will, too. Serving as an irregular dominant, cheek dimples are not apparent in 100 percent of children (even though the dominant gene was inherited). This is very rare, highly unlikely, and often due to what geneticists have determined to be an irregularity that causes dimples to come from multiple genes.

Freckles

Photo by Tyler Mullins

Through the inheritance of at least two dominant genes, individuals are able to develop freckles. The mother’s heterozygous genotype enables her to carry two different gene locus based alleles, with at least one for the freckles. Through the child’s inheritance of this dominant gene, freckles are easily and automatically developed each and every time. In fact, the only possible way that the freckles would not exist is if the child was homozygous. Someone who is homozygous has two equal alleles, both of which fail to produce freckles. In which case, the recessive allele would have to be received without any dominant gene inheritance whatsoever.

Double-Jointedness 

Photo by Dmitry Kotov

Double-jointedness is most present in the hands and serves as one of most common dominant genes in humans. Allowing for an increased range of mobility throughout various parts of the body, double-jointedness is often referred to as hypermobility and affects approximately 5 percent of the entire world. Though these extreme extensions can be fun to show off at times, hypermobility can be related to a variety of other difficulties including fibromyalgia, valve prolapse, and panic attacks.

Through what is known as an autosomal dominant inheritance, certain genes in each cell can cause these disorders. While this is often the result of inheritance from an already affected parent, sporadic gene mutations can also occur in individuals who have no prior family disease. Additionally, if two of the same gene copies are present in these cells through an autosomal recessive type pattern, hyper mobility forms known as dermatosparaxis and kyphoscoliosis can occur. In most cases these issues show up when both parents carry the affected genes but tend to keep their disorder hidden physically, showing no signs or symptoms.

Studies also show that by over extending one joint too much, others can subsequently be affected.

Widow’s Peak 

Photo by Genessa Panainte

While no definite studies have been done on a worldwide scale, it is estimated that the v-shaped hairline known as the “widow’s peak” can be found in more than 80 percent of the entire population.

The gene which causes the widow’s peak to be dominant among humans contains two total alleles. While the recessive straight hairline gene will only work if inherited in a pair of its own, the dominant gene which causes a widow’s peak to be one of the most common dominant genes in humans will always win out if included. In other words, if only one parent has this dominant gene it is possible, but if both have the gene, it is inevitable.

Long Eyelashes

Photo by Sean Brown

Existing among a high percentage of the population, long eyelashes are certainly one of the most common dominant genes in humans. While many other human traits are controlled by multiple genes which operate in a polygenic manner, long eyelashes consist of only two (one dominant and one recessive). If you were to inherit one of each gene (long eyelash gene from one parent and short eyelash gene from the other) that would be considered your genotype. However, if the length of your lashes is indeed long, that is your phenotype since that means the dominant gene won out against the recessive. This means that upon being matched up against another gene of the same trait, the dominant gene (long eyelashes) will always win out.

Each specific gene carries a set of instructions for certain parts of you and often determines your entire physical makeup. However, thanks to the most common dominant genes in humans, traits are often easy to determine.

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About the Creator

Alicia Springer

Mother of two. Personal trainer. Fitness is about determination, not age.

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