Eye colour, or more correctly iris colour, is often used as an example for teaching Mendelian genetics, with brown being dominant and blue being recessive.
Your children inherit their eye colors from you and your partner. It's a combination of mom and dad's eye colors – generally, the color is determined by this mix and whether the genes are dominant or recessive. Every child carries two copies of every gene – one comes from mom, and the other comes from dad.
The allele for brown eyes is the most dominant allele and is always dominant over the other two alleles and the allele for green eyes is always dominant over the allele for blue eyes, which is always recessive.
Fact: Two blue-eyed parents can have a child with brown eyes, although it's very rare. Likewise, two brown-eyed parents can have a child with blue eyes, although this is also uncommon.
People are often very confused by eye color genetics because reality seems to fly in the face of the simple genetics we are taught in school. First, the answer is yes to both questions: two blue-eyed parents can produce green or brown-eyed children.
Determining the rarest eye color... not so straightforward
Green is the rarest eye color of the more common colors. Outside of a few exceptions, nearly everyone has eyes that are brown, blue, green or somewhere in between. Other colors like gray or hazel are less common.
Gray: The Rarest Eye Color
New classifications have determined that gray is its own standard color.1 (It was previously, and incorrectly, lumped in with blue.) With this change, gray now tops the list as the rarest eye color.
According to an article by evolutionary biology professor Mark Elgar, PhD, of the University of Melbourne, blue-eyed redheads are the absolute rarest, with 0.17% of the population having that combination of hair and eye color.
The second-rarest eye color is hazel, a mixture of brown and green with golden flecks. About 18% of Americans have hazel eyes, compared with about 5% of the world's population.
Genetics of Blue Eyes
Both parents have to pass along the blue eye gene in order for their child to have blue eyes. That doesn't necessarily mean that the parents themselves have to have blue eyes; it's possible they carry the gene, but it is recessive.
Because boys have the sex chromosomes XY, they must inherit their Y chromosome from their father. This means they inherit all the genes on this chromosome, including things like sperm production and other exclusively male traits.
The blond allele is recessive, and gets covered up. If two brunette parents have a blond child, they had to have instructions for making blond hair hidden in their DNA. You can think of recessive alleles as t-shirts, and dominant ones as jackets.
The darkest skin color indicates the presence of three dominant alleles (AABBCC). Therefore dark skin is a dominant character. The lightest skin color indicates the presence of recessive alleles (aabbcc). Because melanin is a dominant phenotype, and all-white skin genes are recessive.
Genetically, you actually carry more of your mother's genes than your father's. That's because of little organelles that live within your cells, the mitochondria, which you only receive from your mother.
Unlike nuclear DNA, which comes from both parents, mitochondrial DNA comes only from the mother.
The inheritance of eye color is more complex than originally suspected because multiple genes are involved. While a child's eye color can often be predicted by the eye colors of his or her parents and other relatives, genetic variations sometimes produce unexpected results.
How Rare Is Dirty Blonde Hair? About 2 percent of the population are natural blondes, but it's a very popular hair color because many turn to hair dye to achieve it. Brighter blonde shades like ashy blonde and beige blonde are more popular choices than dirty blonde, so you can consider dirty blonde a bit more unique.
Black hair and blue eyes is a much more rare combination than is blonde hair and blue eyes. The reason why these two traits are linked is that the genes responsible for hair and eye color happen to be close together on the same chromosomes.
Did Elizabeth Taylor have violet eyes? These days, thanks to colored contact lenses, anyone can have violet-colored eyes . Taylor didn't come by her purple peepers that way; the first tinted contact lenses weren't commercially available until 1983. Taylor's eye color was the real deal.
We found that green is the most popular lens colour, with brown coming in a close second, despite it being one of the most common eye colours. Although blue and hazel are seen as the most attractive eye colours for men and women they are surprisingly the least popular.
When broken down by gender, men ranked gray, blue, and green eyes as the most attractive, while women said they were most attracted to green, hazel, and gray eyes. Despite brown eyes ranking at the bottom of our perceived attraction scale, approximately 79% of the world's population sports melanin-rich brown eyes.
Unbelievable as it may seem, the answer is yes—natural purple eyes do exist. Purple eyes are also commonly referred to as “violet eyes,” as they are typically a light shade. For most people, this striking eye color can only be achieved with the help of colored contacts.
The highest concentration of people with green eyes is found in Ireland, Scotland, and northern Europe. In fact, in Ireland and Scotland, more than three-fourths of the population has blue or green eyes – 86 percent! Many factors go into having green eyes.
Eye Color Changes Not Related to the Iris
Arcus senilis is a hazy blue or white ring on the cornea from a build-up of a natural fatty substance called lipids. It's common with aging and usually harmless. Most seniors have some degree of arcus senilis.