Can a Brown Eyed Woman Have a Blue Eyed Baby?

Eye color is determined by the amount and type of pigments present in the iris. The color of a baby's eyes is usually determined by the parents' eye colors.

Genetics of Eye Color

Eye color is a polygenic trait, which means that it is controlled by multiple genes. The two main genes that determine eye color are OCA2 and HERC2. These genes work together to produce and distribute melanin, the pigment that gives color to our skin, hair, and eyes.

Dominant and Recessive Genes

Each gene has two alleles, or variants, that can be dominant or recessive. Dominant alleles are expressed even if there is only one copy of the gene, while recessive alleles are only expressed if both copies of the gene are recessive.

In the case of eye color, brown is a dominant allele, while blue is a recessive allele. This means that if a person has one brown allele and one blue allele, they will have brown eyes, since brown is dominant. However, they can still pass on the blue allele to their children.

Predicting Eye Color

Since eye color is determined by multiple genes, predicting it accurately is not always possible. However, there are some tools that can give us an idea of the probabilities of certain eye colors based on the parents' eye colors.

One such tool is the Punnett square, a diagram that helps predict the possible outcomes of a genetic cross. In the case of eye color, the Punnett square can show us the probabilities of different eye colors based on the parents' genetic makeup.

Punnett Square Example

In this example, both parents have one brown allele and one blue allele. The Punnett square shows us that there is a 75% chance of the baby having brown eyes (either BB or Bb), and a 25% chance of the baby having blue eyes (bb).

So, can a brown eyed woman have a blue eyed baby? Yes, it is possible if both parents carry the recessive blue allele. However, the probabilities of this happening depend on the parents' genetic makeup and cannot be predicted with certainty.