Eye color genetics is complex, with multiple genes from each parent determining a person’s eye color.
A baby’seye colordepends on the amount and bang out of melanin in theiris.
While mostly a physical trait, eye color can sometimes indicate a health issue.
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A newborn’s eye color is usually related to their skin tone.
White babies tend to be born with blue or sometimes gray eyes.
Black, Hispanic, and Asian babies commonly have brown or black eyes.
Ababy’s eye color may changeover time.
Are All Babies Born with Blue Eyes?
Each gene has two versions, called alleles.
You inherit one allele from your mother and one from your father.
For a recessive trait like blue eyes to appear, both alleles must be the same (homozygous).
In general, darker eye colors are more dominant.
Brown eyes are dominant, while blue eyes are recessive.
Green eyes are a mixrecessive to brown but dominant to blue.
Even though green eyes are dominant over blue, they are still one of the rarest eye colors.
All people with blue eyes can trace their ancestry back to a single common ancestor.
Can Two Blue-Eyed Parents Have a Brown-Eyed Child?
It is possible for two blue-eyed parents to have a brown-eyed child.
Blue eye color is recessive while brown eye color is dominant.
That said, the Punnett square is not a perfect method for predicting complex inheritance patterns.
For example, it suggests that two blue-eyed parents cannot have a brown-eyed child.
Determining each parents alleles can be tricky.
To identify these recessive traits, it helps to know the eye colors of the grandparents.
Heterochromia often presents as one blue eye and one brown eye.
Waardenburg syndrome is a genetic condition that can cause hearing loss in one or both ears.
People with Waardenburg syndrome may also be born with very pale eyes or one eye that is two colors.
Ocular Albinism
Very pale blue eyes may be caused byocular albinism.
This comes up whenever there is no pigment in the iris.
Most people with ocular albinism are male.
The gene for ocular albinism is recessive but it is located on the X chromosome.
Since women have two X chromosomes, the recessive gene is typically hidden by another normal gene.
Although women with the gene are considered carriers, they will not usually have the condition themselves.
Studies suggest fewer than one out of every 60,000 men has ocular albinism.
Aniridia is bilateral, meaning that it affects both eyes at the same time.
The condition causes the pupil to look large and unevenly shaped.
Eyes affected by aniridia have difficulty adjusting to light, resulting in blurry vision and light sensitivity.
Aniridia is because of mutations in the PAX6 gene.
This gene plays an important role in forming tissues and organs during an embryo’s development.
Summary
A baby’s eye color is determined by genetics.
Eye color is a combination of pigments produced in the stroma.
Brown eyes have more melanin than green or hazel eyes.
Blue eyes have very little pigment.
The mix of genes inherited from each parent determines which pigments are produced and the baby’s eye color.
These genes can also lead to certain congenital conditions that may affect vision.
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