Parents with green eyes: what colour will the baby's eyes be?
Green eyes are the most likely, at 75%. The full odds: green 75% and blue 25%. In this simple model, brown eyes are not possible, though real life can still surprise you.
Most likely eye colour
Green
“Unlikely” means 0% in this model. In real life it can still happen, because many more genes shape eye colour.
Many babies are born with lighter eyes that darken during the first year. The colour has usually settled by the first birthday and can still shift a little until about age 3.
Estimate from a two-gene model that assumes each parent carries hidden versions of both genes.
A simplified estimate for fun. Real genetics is more complex.
How we work it out
The model uses two genes. bey2 has a brown version (B) and a blue one (b); gey has a green version (G) and a blue one (b). Each parent passes on one version of each gene, so each parent has four equally likely combinations and the square has 16 boxes. Any B gives brown eyes; otherwise any G gives green; otherwise the eyes are blue.
A green-eyed parent has two blue versions of bey2 and is assumed to carry a hidden blue version of gey: bey2 bb, gey Gb.
| b G | b b | b G | b b | |
|---|---|---|---|---|
| b G | green | green | green | green |
| b b | green | blue | green | blue |
| b G | green | green | green | green |
| b b | green | blue | green | blue |
- Green: 12 of 16 boxes
- Blue: 4 of 16 boxes
Frequently asked questions
Can parents with green eyes have a baby with brown eyes?
Not in this simple model. Eye colour really depends on many genes, so it can still happen, but it is rare.
Can parents with green eyes have a baby with green eyes?
Yes. In the two-gene model it happens 75% of the time.
Can parents with green eyes have a baby with blue eyes?
Yes. In the two-gene model it happens 25% of the time.
- MedlinePlus Genetics (US National Library of Medicine): Is eye color determined by genetics?
- The Tech Interactive, Ask a Geneticist: What are the chances my child will have red hair and blue eyes?
- Eiberg H, Mohr J. Major genes of eye color and hair color linked to LU and SE. Clinical Genetics 1987;31(3):186-191
- American Academy of Ophthalmology: 20 Things to Know About Children's Eyes and Vision
- Jabbehdari S et al. Colour change in the newborn iris: 2-year follow-up of the Newborn Eye Screening Test study. Acta Ophthalmologica 2019