Quick Answer
No, it is genetically impossible for two blue eyed parents to have a child with hazel eyes. For a child to have hazel eyes, they must inherit one gene for blue/green eyes and one gene for brown eyes. Two blue eyed parents can only pass on genes for blue/green eyes, so their child cannot be hazel eyed. The only way two blue eyed parents could have a hazel eyed child is through a very rare genetic mutation.
Eye Color Genetics
To understand why two blue eyed parents cannot have a hazel eyed child, we need to understand some basics about eye color genetics. Human eye color is determined by the amount of melanin (pigment) in the iris of the eye. The main genes that influence eye color are:
- HERC2 – Tells the body to make a lot of melanin which results in brown eyes.
- OCA2 – Tells the body to make less melanin which results in blue/green eyes.
We each inherit one copy of the HERC2 and OCA2 genes from each parent. The combinations of these genes determine our eye color:
| Gene Combination | Eye Color |
|---|---|
| HERC2/HERC2 | Brown |
| HERC2/OCA2 | Hazel or Brown |
| OCA2/OCA2 | Blue/Green |
As you can see, hazel eyes require inheriting one HERC2 gene (for brown eyes) and one OCA2 gene (for blue/green eyes).
Blue Eyed Parents
Two blue eyed parents can only pass on OCA2 genes for reduced melanin production. They do not have any HERC2 genes to pass on. Therefore, their children will inherit OCA2 genes from both parents and end up with blue or green eyes.
The only way for two blue eyed parents to have a hazel eyed child is if a new HERC2 mutation arises. But mutations like this are extremely rare. The chances of this happening are less than 1 in a billion.
Other Eye Colors Explained
While hazel is not possible, here is what other eye colors two blue eyed parents can have:
Blue Eyes
This is the most likely outcome. If both parents pass on OCA2 genes, the child will have blue eyes like them.
Green Eyes
A simple variation of blue eyes. The child inherits OCA2 genes from both parents but has slightly more melanin than blue eyed family members.
Gray Eyes
These are blue eyes with a gold/brown ring around the pupil. Caused by a very slight increase in melanin. Still requires two OCA2 genes.
Brown Eyes
Extremely unlikely but theoretically possible if both parents have a dormant HERC2 gene that becomes activated. Again, the odds are less than 1 in a billion.
What About Recessive Genes?
Some people think hazel eyes could skip a generation if both parents carry recessive HERC2 genes. However, there are two reasons this cannot happen:
- Blue eyes are recessive. If the parents had brown eye genes, even recessively, they would have brown eyes themselves.
- Recessive genes still have a 25% chance of being expressed. There would be family history of brown/hazel eyes.
So scientifically it is impossible for two visibly blue eyed parents to carry HERC2 genes, either dominantly or recessively.
Exception – Chimerism
There is one extraordinarily rare exception where two blue eyed parents could have a hazel eyed child. This is if one of the parents is a chimera.
Chimerism happens when two fertilized eggs fuse together into one individual. This can result in the person having two distinct sets of DNA.
If a blue eyed chimera had one set of OCA2 DNA and a hidden set of HERC2 DNA, they could potentially pass on the HERC2 genes. This could allow two blue eyed parents to have a hazel eyed child.
But chimerism is incredibly rare, estimated at only 1 in 50,000 people. And the specific genetics to allow hazel eyed offspring would make it even more unlikely.
Conclusion
In conclusion, it is scientifically impossible for two visibly blue eyed parents to produce a hazel eyed child together under normal genetic circumstances.
The only way this could occur is through:
- An extremely rare new mutation leading to HERC2 gene formation.
- An even rarer case of complex genetic chimerism.
So while intriguing outliers may occasionally occur, the vast majority of blue eyed couples can be certain any hazel eyed children are not both genetically theirs. Eye color genetics follow very predictable inheritance patterns in most human reproduction.
More Questions?
Here are answers to some other common questions about eye color inheritance:
Can two brown eyed parents have a blue eyed child?
Yes, this is possible if both parents carry recessive OCA2 genes. Each brown eyed parent has a 25% chance of passing on the recessive blue eye gene in each pregnancy.
Can a blue eyed parent and brown eyed parent have a blue eyed child?
Yes. The blue eyed parent will pass on an OCA2 gene. As long as the brown eyed parent contributes an OCA2 recessive gene as well, the child will have blue eyes. There is a 50% chance of the brown eyed parent passing on their recessive gene.
Can a blue eyed parent and brown eyed parent have a green or hazel eyed child?
Yes. The blue eyed parent contributes an OCA2 gene for low melanin. The brown eyed parent contributes a HERC2 gene for high melanin. This combination results in an intermediate eye color we call green or hazel.
At what age are a child’s eye color permanent?
Eye color continues to develop through infancy. Usually by age 3, the final eye color is set. Some subtle changes can occur into the early teens but the main genetic color is established much earlier on.
Can eye color change later in life?
In rare cases, trauma, disease, or aging can slightly alter eye color over time. But the underlying genetic color remains unchanged. Environment and lifestyle do not impact genetic eye color inheritance.
Do all genetic siblings have the same eye color?
No, genetic siblings can often have different eye colors based on the specific gene combinations they inherit. Except for identical twins, siblings have unique mixes of the parental genes.
Is eye color determined by just one gene?
No, multiple genes influence eye color including OCA2, HERC2, SLC24A4, TYR, and SLC45A2. Interactions between these genes create a spectrum of human eye colors.
Can someone have two different colored eyes?
Yes, this rare condition is known as heterochromia iridum. It is often caused by uneven melanin levels between the left and right irises during fetal development.
I hope these additional questions provide more context on the intriguing genetics behind human eye color inheritance! Let me know if you need any clarification or have additional questions on this topic.