As a subject matter expert in genetics and human physical traits, I can provide you with an informed answer on the rarity of having brown hair and blue eyes.

Hair and eye color are determined by multiple genes, and the combination of brown hair with blue eyes is not as common as some other combinations, such as brown hair with brown eyes. Blue eyes are a recessive trait, meaning both parents must carry the gene for blue eyes for their child to have blue eyes. Brown hair, on the other hand, is a dominant trait, so it can be expressed even if only one parent carries the gene for brown hair.

According to various studies, blue eyes are most commonly found in people of European descent, particularly in those from Northern European countries. Brown hair is more universally common across different ethnic groups. The specific frequency of the combination of brown hair and blue eyes can vary significantly by region and ethnicity. For instance, in some Northern European populations, where blue eyes are more prevalent, the combination might be less rare than in other parts of the world where blue eyes are less common.

It's important to note that the rarity of a trait is also influenced by the population's genetic diversity and historical migrations, which can affect the distribution of genes for hair and eye color.

read more >>

The combination of having both red hair and blue eyes is so rare because blue eye color is also a recessive trait, meaning both parents must carry the gene for a child to have it. ... The majority of redheads have brown, hazel, or green eyes.read more >>