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Is Hazel eye color dominant or recessive?

By: Author Color With Leo

Hazel eyes are one of the most fascinating and unique eye colors. They appear to shift between shades of brown, green, gray, and orange. But what determines whether someone has hazel eyes? Is it a dominant or recessive genetic trait? Here we will explore the genetics behind hazel eyes and whether they are dominant or recessive.

What are hazel eyes?

Hazel eyes are multicolored eyes that contain shades of brown, green, orange, grey, and blue. The mixture of pigments within the iris causes hazel eyes to appear to shift colors in different lighting conditions. Central heterochromia is very common in hazel eyes, where there is a darker ring around the pupil and a lighter outer iris color. No two sets of hazel eyes are exactly alike.

The varying color in hazel eyes is caused by a phenomenon called Rayleigh scattering. This is the same phenomenon that makes the sky appear blue. Light enters the eye and reflects off the different pigment molecules in the iris. The reflected colors combine to create the hazel appearance.

Genetics of eye color

Eye color is a polygenic phenotypic character, meaning multiple genes influence the final eye color. The main gene that controls eye color is OCA2 on chromosome 15, which codes for the P protein. The P protein is involved in the production of melanin, which gives color to the skin, hair, and eyes. Variants of the OCA2 gene reduce the amount of melanin produced, leading to lighter eye colors like green and blue.

Here is a simple overview of the genetics of eye color:

  • Brown eyes = dominant (BB or Bb)
  • Green eyes = recessive (bb)
  • Blue eyes = recessive (bb)

However, many other genes also influence eye color, including OCA2, SLC24A4, TYR, SLC45A2, and IRF4. The interaction between all these genes accounts for the range of human eye colors.

Are hazel eyes dominant or recessive?

Hazel eyes are neither dominant nor recessive. They fall somewhere in between as an intermediate eye color. Most experts consider hazel eyes to be a variation of brown eyes. Brown eye color is dominant over green and blue eye colors. However, hazel eyes have an additional mingling of lighter pigments that lightens the overall eye color.

Research has found that people with hazel eyes tend to have a mix of variants in the OCA2 and HERC2 genes. They usually have at least one dominant allele for brown eye color (B), but also have variants in other genes that dilute the brown and allow green and other colors to show through.

What causes hazel eyes?

Hazel eyes arise from a combination of variants in multiple genes that control eye color. The exact genetic recipe that leads to hazel eyes is not fully understood, but some key factors are:

  • At least one dominant brown allele (B) of the OCA2 gene.
  • Variant(s) in the OCA2 promoter region that reduce expression of the OCA2 gene, leading to less melanin pigment.
  • Variant(s) in other pigmentation genes like HERC2, SLC24A4, TYR, and IRF4 that dilute brown melanin.

Together, these genetic factors result in eyes with a mixed hazel appearance, rather than a definitive brown, green or blue. The unique blending of pigments in hazel eyes leads to the multicolored, shifting appearance.

What affects hazel eye color?

Several factors can influence the exact shade and pattern of colors seen in hazel eyes:

  • Melanin content – More melanin leads to more brown, less leads to more green/light areas.
  • Rayleigh scattering – Causes different wavelengths of light to reflect back and add color.
  • Lighting conditions – Hazel eyes appear to change color in different lighting.
  • Age – Hazel eyes can get lighter or darker with age as melanin levels change.

This unique combination of variables is why no two hazel eyes are the same. Some may appear more brown or green, while others show a fairly even mix of colors.

Hazel eyes and genetics

Here is a summary of some key genetics facts about hazel eyes:

  • Hazel eyes are not a simple Mendelian dominant/recessive trait.
  • Multiple genes influence hazel eye color, including OCA2, HERC2, SLC24A4, TYR, IRF4.
  • Hazel eyes typically contain at least one dominant brown allele (B) of the OCA2 gene.
  • Additional gene variants reduce melanin production and allow green/blue colors to show through.
  • The interaction of all these genes produces the hazel eye phenotype.
  • The exact genetic recipe behind hazel eyes is not fully understood.

What is the rarest eye color?

Globally, brown eyes are the most common, while blue eyes are the rarest eye color. Green eyes are rare among Asian and African populations. However, some of the rarest eye colors include:

  • Amber eyes – Very light, golden honey-brown color. Extremely rare globally.
  • Red/violet eyes – Only seen in people with severe albinism who lack melanin.
  • Heterochromia – Having two different colored eyes, like blue and brown. Quite rare.

Hazel eyes are definitely among the rarer eye colors seen in humans, although not as exceptionally rare as red/violet albinism eyes or complete heterochromia.

Are hazel eyes attractive?

Hazel eyes are often considered very beautiful and exotic looking. Some reasons hazel eyes are seen as attractive include:

  • Rare – Hazel eyes are relatively uncommon compared to brown, blue, and green eyes.
  • Multicolored – The mix of shades stands out compared to solid brown, blue eyes.
  • Mysterious – Hazel eyes seem to change color drawing interest and intrigue.
  • Complex pattern – The flecks of color create a kaleidoscope effect.

However, perceptions of attractiveness are highly subjective and individual. While many do find hazel eyes gorgeous and captivating, other eye colors such as blue can also be very striking and beautiful!

How common are hazel eyes?

Hazel eyes are one of the two rarest eye colors along with amber eyes. Here are some statistics on the frequency of hazel eyes:

  • About 5-10% of people worldwide have hazel eyes.
  • Most common in people of European descent, especially Northern Europeans.
  • More common in women than men.
  • Rarer in people of Asian, African and Hispanic descent.
  • Nearly absent among indigenous Arctic populations.

In comparison, brown eyes comprise 70-90% of global eye colors with blue being second most common at around 8-10%. Green eyes make up around 2% of the global population.

Famous people with hazel eyes

Many celebrities have popularized hazel eyes. Here are a few famous people rocking their beautiful hazel eye color:

  • Adriana Lima
  • Cara Delevingne
  • Jennifer Lopez
  • Jennifer Aniston
  • Harry Styles
  • Chris Pine
  • Paul Rudd
  • Shawn Mendes

Conclusion

In summary, hazel eyes are not a simple dominant or recessive trait when it comes to genetics. They arise from a complex interaction between multiple genes that control eye pigmentation and melanin production. Hazel eyes contain elements of brown, along with variant alleles that allow for the inclusion of green, grey, and orange hues. This makes hazel eyes an intermediate multicolored blend of eye colors that shifts between shades. Hazel eyes are among the rarest eye colors globally but stand out beautifully due to their captivating, heterogeneous appearance.