Gray Eyes: Why Does My Child Have Them?

July 8, 2024

Gray eyes are a fascinating and relatively rare feature that can spark curiosity and questions, although they can be quite common in newborns.

This article will explore the reasons behind gray eyes in children, how eye color is defined, who tends to have this particular shade, and how it may change over time.

How is eye color defined?

Eye color is determined by the amount and type of pigment called melanin present in the iris, the colored part of the eye that surrounds the pupil.

Melanin is produced by specialized cells called melanocytes.

The amount, type, and distribution of melanin in the iris determine the perceived color of the eyes.

There are two main types of melanin involved in eye color:

  • Eumelanin: responsible for brown and black colors
  • Pheomelanin: responsible for red and yellow colors

The combination and concentration of these pigments create the wide range of eye colors we observe, including brown, black, blue, green, hazel, and gray.

Gray eyes occur when there is a very small amount of melanin in the iris, combined with a particular structure of the iris tissue that scatters light in such a way that it appears gray.

Who has gray eyes?

Gray eyes are relatively rare in the global population.

They are more common among people of European descent, particularly in Northern and Eastern European regions. Countries such as Russia, Finland, Estonia, and Latvia have a higher percentage of people with gray eyes compared to other parts of the world.

Genetically, gray eyes are associated with specific variants of genes involved in melanin production and distribution. Some of the main genes involved include:

  • OCA2 (oculocutaneous albinism II gene) Variants of this gene influence the amount of melanin produced, with the A/A genotype associated with more melanin and darker eyes, while the G/G genotype with less melanin and lighter eyes.
  • HERC2 (HECT and RLD domain containing E3 ubiquitin protein ligase 2 gene) This gene regulates the expression of the OCA2 gene, indirectly influencing melanin production in the iris.
  • SLC24A4 (solute carrier family 24 member 4 gene) Variants of this gene are associated with differences in eye color, including gray.
  • TYRP1 (tyrosinase-related protein 1 gene) This gene encodes an enzyme involved in melanin synthesis, with variants associated with different shades of eye color. Variants of these genes that lead to reduced melanin production can contribute to the appearance of gray eyes.

Why does the newborn have gray eyes?

It’s common for newborns, especially those of Caucasian origin, to be born with gray or light blue eyes. This phenomenon is due to several factors:

  • Lack of melanin: at birth, the melanocytes in the iris have not yet begun to produce significant amounts of melanin.
  • Iris structure: the iris of newborns has a different structure compared to that of adults, with fewer layers of collagen.
  • Tyndall effect: light scattering through the lightly pigmented iris creates an optical effect that makes the eyes appear blue or gray.
  • Gradual development: melanin production in the iris begins after birth and continues in the first months and years of life.

It’s important to note that eye color at birth is not necessarily indicative of the final color.

Many children born with gray or light blue eyes will gradually develop their definitive eye color within the first 3 years of life, although some changes may continue into adolescence.

What are gray eyes called?

Gray eyes don’t have a specific scientific name, but they are described in various ways depending on their shade and appearance:

  • Pure gray eyes: When the iris appears uniformly gray without other evident hues.
  • Blue-gray eyes: When there’s a bluish tint in the gray, often due to the Tyndall effect.
  • Green-gray eyes: When slight green tones are present in the base gray.
  • Steel gray eyes: To describe a particularly intense and metallic gray.
  • Silver gray eyes: When the gray has a bright, reflective appearance.
  • Storm gray eyes: To indicate a dark and intense gray, similar to the color of storm clouds.

These terms are more descriptive than scientific and are often used in literary or aesthetic contexts to capture the unique nuances of gray eyes.

How many adults have gray eyes?

The exact prevalence of gray eyes in the global adult population is difficult to quantify precisely, as it varies significantly among different populations and geographic regions. However, we can provide some estimates based on studies and observations:

It’s estimated that less than 3% of the world’s population has gray eyes.

There are regional variations, for example, in some parts of Northern Europe, the percentage may rise to 5-8% of the population, while in populations of African or Asian origin, gray eyes are extremely rare, with a prevalence of less than 0.1%.

In comparison to other colors, these are the estimated statistics:

  • Brown: About 55-79% of the world’s population
  • Blue: About 8-10% of the world’s population
  • Green: About 2% of the world’s population

The presence of gray eyes is influenced by genetics, which is why it’s more common in populations with a genetic history of reduced pigmentation, such as those of Northern European origin.

Additionally, there is some variability in iris color classification; the distinction between gray eyes and other light shades (such as light blue or light green) can be subjective, influencing statistics.

It’s important to note that these figures are approximate and may vary depending on the studies and classification criteria used.

gray eyes

What influences eye color over time?

Eye color, including gray, can undergo variations throughout an individual’s life. Several factors can influence these changes:

Early childhood development

As we mentioned, melanin production in the iris gradually increases after birth.

Eye color generally stabilizes by 3-5 years of age, but can continue to change into adolescence in some cases.

Genetic factors

Genes controlling melanin production and distribution can be activated or deactivated at different stages of life.

Some people may experience changes in eye color during puberty due to hormonal changes affecting gene expression.

Light exposure

Prolonged exposure to sunlight can stimulate melanin production in the iris, leading to a slight darkening of eye color over time.

Medical conditions

Some diseases, such as Horner’s syndrome or heterochromia, can cause changes in eye color.

Inflammation or injuries to the eye can temporarily or permanently alter the color of the iris.

Medications

Some medications, such as those used to treat glaucoma (e.g., prostaglandins), can cause a change in eye color as a side effect.

Aging

With age, the structure of the iris can change, affecting how light is reflected and perceived.

Some individuals may notice a slight lightening of eye color with advancing age.

Nutrition

Although less significant, some studies suggest that diet may slightly influence eye color, particularly the intake of foods rich in melanin.

Stress and emotional factors

Changes in pupil dilation due to stress or emotions can affect the perception of eye color, even if they don’t actually alter the base color.

It’s important to emphasize that while small variations in eye color can occur throughout life, drastic or sudden changes should be evaluated by an ophthalmologist, as they could indicate an underlying medical condition.

For parents of children with gray eyes, it’s reassuring to know that this characteristic is perfectly normal and can be a source of uniqueness and beauty.

However, as with any aspect of a child’s health, it’s always advisable to discuss any concerns or significant changes with the pediatrician or a pediatric ophthalmologist.

We are with you.

At Parentalife, we are by your side throughout your parenting journey. We understand that every aspect of your child’s development, including eye color, can raise questions and curiosity.

Our commitment is to support parents with informative guides, educational courses, and personalized consultations, to help you navigate confidently through all stages of your child’s growth.

SOURCES

Dorgaleleh S, Naghipoor K, Barahouie A, Dastaviz F, Oladnabi M. Molecular and biochemical mechanisms of human iris color: A comprehensive review

About the Author

Severino Cirillo

Health, Wellness and Education Expert. With a degree in Community Health, he is the CEO of Informed Parent and is responsible for validating the blog's scientific information and coordinating the editorial team of experts, consisting of gynecologists, midwives, psychotherapists, and others in pregnancy, perinatal, and parenting wellness and health.