Baby Eye Color Predictor
Estimate the chances of a baby's eye colour from the parents' eye colours.
About the Baby Eye Color Predictor
This uses the classic simplified two-gene model (bey2 and gey): a brown allele masks the others, green masks blue, and blue shows only when no brown or green allele is present. It assumes brown- and green-eyed parents each carry one hidden blue allele, the case that gives the familiar textbook percentages.
In reality eye colour involves many genes (OCA2/HERC2 has the largest effect), so a baby can have a colour this model doesn't predict. Babies' eye colour can also change until about age 3.
The formula
P(brown) = P(any B); P(green) = P(no B) × P(any G); P(blue) = P(no B) × P(no G)
Worked example
Example: Most likely = Green
- Inputs: Parent 1 eyes: Green / hazel; Parent 2 eyes: Blue.
- Formula: P(brown) = P(any B); P(green) = P(no B) × P(any G); P(blue) = P(no B) × P(no G)
- Result: Most likely = Green
Things to keep in mind
- For fun and learning only; it can't predict real outcomes with certainty.
Questions people ask
Can two blue-eyed parents have a brown-eyed child?
Rarely, yes; other genes are involved beyond this model.
When is eye colour final?
Usually by 6–12 months, sometimes up to 3 years.