Having bluish gray eyes is considered quite rare globally, occurring in less than 1% of the world’s population. However, the prevalence varies greatly depending on geographic region and ethnicity. Here is a closer look at the rarity of bluish gray eyes.
Global Prevalence
On average, only around 0.8% of the global population has bluish gray eyes. This makes it one of the rarest eye colors worldwide. The most common eye colors globally are brown and black, accounting for over 75% of people. Bluish gray eyes fall into the category of light eyes, along with blue, green, hazel, and amber eyes. Together, light eyes make up less than 17% of the world’s population.
Prevalence by Region
The prevalence of bluish gray eyes varies significantly across different regions and ethnicities. They are most common in Northern and Eastern Europe, where light eyes in general tend to be most prevalent. Countries like Finland, Estonia, and Latvia have some of the highest percentages of light eyes, up to almost 90% of the population. However, even in Northern Europe, true bluish gray eyes are still rare compared to pure blue eyes.
In Southern Europe and Western Asia, the percentage of light eyes drops to between 20-40% on average. Here, bluish gray eyes would account for a very small fraction of people. In sub-Saharan Africa, East Asia, South Asia, Southeast Asia, and Indigenous populations of the Americas and Australia, light eyes are extremely rare, with a prevalence of less than 5%.
Prevalence by Ethnicity
Looking more closely at prevalence by ethnicity:
| Ethnicity | Prevalence of Bluish Gray Eyes |
|---|---|
| Northern European (Scandinavian, Baltic, Northwest Russian) | 0.5-2% |
| Eastern European (Polish, Ukrainian, Northeast Russian) | 0.2-1% |
| Southern European (Spanish, Italian, Greek) | Less than 0.1% |
| Western Asian (Turkish, Armenian, Iranian) | Less than 0.1% |
| Eastern European Jewish | 0.1-0.5% |
| Northern Middle Eastern (Lebanese, Syrian) | Less than 0.1% |
| Indigenous American | Extremely rare |
| East Asian (Chinese, Japanese, Korean) | Extremely rare |
| Southeast Asian | Extremely rare |
| South Asian (Indian, Pakistani) | Extremely rare |
| Indigenous Australian | Extremely rare |
| Sub-Saharan African | Extremely rare |
As the table shows, Northern and Eastern Europeans have the highest percentages of bluish gray eyes in the range of 0.2-2% typically. Southern Europeans, Western Asians, and Eastern European Jewish populations have slightly lower percentages in the 0.1-0.5% range. In most other ethnicities globally, true bluish gray eyes are extremely rare or almost non-existent.
Causes of Rarity
The rarity of bluish gray eyes globally is mainly attributed to two genetic factors:
- Low prevalence of the gene variants required to produce light eye colors
- Low prevalence of the specific modifiers required to produce grayish hues
To have bluish gray eyes, a person needs to inherit two copies of the recessive gene variants for light eyes, such as those in the OCA2 and HERC2 genes. These variants are rare outside of Europe. Additionally, bluish gray eyes require unique combinations of genetic modifiers that dilute and mix the melanin pigment in the iris to create grayish hues. These modifiers are even rarer globally.
Difference from Blue Eyes
Bluish gray eyes are distinct from pure light blue eyes in their muted, grayish hue. While blue eyes contain low levels of melanin overall, bluish gray eyes have slightly more melanin deposited in the anterior border of the iris. This additional melanin neutralizes the brilliant blue into a softer gray-blue. The result is an eye color that shifts between blue and gray depending on lighting conditions.
In dim lighting, bluish gray eyes can appear very similar to blue eyes. But in brighter lighting, the grayish hues become more apparent. The extra melanin content also makes bluish gray eyes typically a bit darker than icy light blue eyes.
Difference from Gray Eyes
Bluish gray eyes differ from true gray eyes in exhibiting some blue pigmentation. While gray eyes have an even, uniform gray tone across the iris, bluish grays have visible hints of light blue throughout. The blue may be more pronounced around the rim of the iris, while the inner areas shift more solidly into gray.
True gray eyes are even rarer than bluish gray eyes globally. They lack the blue hue because they have higher levels of melanin deposited throughout the anterior border of the iris. This uniformly mixes the melanin pigment with the ground color to create a pure gray shade.
Difference from Hazel Eyes
Bluish gray eyes are also distinct from hazel eyes, which shift between shades of light brown and greenish-brown. The brown color comes from higher levels of melanin in hazel eyes compared to bluish gray eyes. While hazel eyes may contain small blue/gray flecks, they do not exhibit the even blue-gray mixing that produces a true bluish gray hue.
Rarity in the United States
In the diverse American population, bluish gray eyes are also quite rare, occurring in less than 1% of people. However, the prevalence is higher among Americans of Northern European descent, estimated at 0.5-1%. This is because early settlers to the U.S. included large numbers of immigrants from countries like England, Ireland, Germany and Scandinavia where light eyes are more common.
A 2015 study of self-reported eye color in over 5 million U.S. citizens found that bluish gray eyes accounted for only 0.7% of the responses. In contrast, light blue eyes were reported by 17% of respondents. So bluish gray eyes are estimated to be around 25 times rarer than blue eyes in the U.S. population.
Summary
In summary, bluish gray eyes are globally rare, occurring in less than 1% of people worldwide. Prevalence is highest in Northern and Eastern Europe at 0.2-2%, and drops significantly in other regions. Bluish grays arise from a unique combination of genetic variants and modifiers that produce their muted grayish-blue color. While similar to blue eyes, bluish grays have more melanin pigment that neutralizes the blue. Their rarity makes them a unique and striking eye color.
