How Can Two Parents With Brown Eyes Have A Child With Blue?
- Pieter Maas
Is it possible for two brown eyed people to have a child with blue eyes? Editor’s Note (4/14/2021): The following article and diagrams present an over-simplified, outdated version of eye color genetics. Eye color is influenced by at least 50 genes, not all of which are well understood.
Yes. The short answer is that brown-eyed parents can have kids with brown, blue or virtually any other color eyes. Eye color is very complicated and involves many genes. To begin to understand how parents with brown eyes could have blue-eyed children, let’s imagine that eye color is due to a single gene, EYCL3, which comes in two versions or alleles, brown ( B ) and blue ( b ).
Remember that for most genes (including eye color), you have two copies of each gene, and that you inherited one from your mother and one from your father. The brown version of the eye color gene ( B ) is dominant over the blue version ( b ). Dominant means that if either of your genes is the B version, then you will have brown eyes.
- Genetically speaking, then, people with brown eyes could be either BB or Bb while people with blue eyes could only be bb,
- Example of a one-gene model for eye color.
- For two parents with brown eyes to have a blue-eyed child, both parents must genetically be Bb,
- When this happens, there is a 1 in 4 chance that these parents will have a bb child with blue eyes.
Unfortunately, eye color is not as simple as this. Besides the EYCL3 gene described above, at least two other genes, EYCL1 and EYCL2, are also involved. Although this set of genes explains how people can have green eyes, it does a poor job of explaining how blue-eyed parents could have brown-eyed children or how anyone can have hazel or gray eyes at all.
- To understand green eyes in all of this, we only need to review EYCL1 and EYCL3 (EYCL2 is a poorly understood brown eye color gene).
- Remember, EYCL3 has two versions, brown ( B ) and blue ( b ).
- EYCL1 also comes in two versions, green ( G ) and blue ( b ).
- The way these genes work is that if you have a B allele, you will have brown eyes ( B is dominant over b and G ), if you have a G allele and no B allele, you will have green eyes ( G is dominant over b ) and if you have all b genes, then you will have blue eyes.
Example of a two-gene model for eye color. I hope this helps to answer your question. As you can tell, while some progress has been made, eye color is a very complex, polygenic trait that is not yet fully understood. : Is it possible for two brown eyed people to have a child with blue eyes?
Can both parents have brown eyes but baby has blue?
Brown eye colour is dominant over blue eye colour. Therefore, for the brown-eyed parents having blue-eyed child, the possibility is that both have heterozygous genotype i.e. Bb. Therefore, from the square below, it is clear that there is a 25% possibility of blue-eyed (bb) child.
How does my child have blue eyes when both parents are brown?
Blue eyes – A clue to paternity Before you request a paternity test, spend a few minutes looking at your child’s eye color. It may just give you the answer you’re looking for. According to Bruno Laeng and colleagues, from the University of Tromso, Norway, the human eye color reflects a simple, predictable and reliable genetic pattern of inheritance.
Their studies1, published this week in the Springer journal Behavioral Ecology and Sociobiology, show that blue-eyed men find blue-eyed women more attractive than brown-eyed women. According to the researchers, it is because there could be an unconscious male adaptation for the detection of paternity, based on eye color.
The laws of genetics state that eye color is inherited as follows:
If both parents have blue eyes, the children will have blue eyes. If both parents have brown eyes, a quarter of the children will have blue eyes, and three quarters will have brown eyes. The brown eye form of the eye color gene (or allele) is dominant, whereas the blue eye allele is recessive.
It then follows that if a child born to two blue-eyed parents does not have blue eyes, then the blue-eyed father is not the biological father. It is therefore reasonable to expect that a man would be more attracted towards a woman displaying a trait that increases his paternal confidence, and the likelihood that he could uncover his partner’s sexual infidelity.
Eighty-eight male and female students were asked to rate facial attractiveness of models on a computer. The pictures were close-ups of young adult faces, unfamiliar to the participants. The eye color of each model was manipulated, so that for each model’s face two versions were shown, one with the natural eye color (blue/brown) and another with the other color (brown/blue).
Could two blue eyed parents have a brown eyed child?
The participants’ own eye color was noted. Both blue-eyed and brown-eyed women showed no difference in their preferences for male models of either eye color. Similarly, brown-eyed men showed no preference for either blue-eyed or brown-eyed female models.
- However, blue-eyed men rated blue-eyed female models as more attractive than brown-eyed models.
- In a second study, a group of 443 young adults of both sexes and different eye colors were asked to report the eye color of their romantic partners.
- Blue-eyed men were the group with the largest proportion of partners of the same eye color.
According to Bruno Laeng and colleagues, “It is remarkable that blue-eyed men showed such a clear preference for women with the same eye color, given that the present experiment did not request participants to choose prospective sexual mates, but only to provide their aesthetic or attractiveness responsesbased on face close-up photographs.” Blue-eyed men may have unconsciously learned to value a physical trait that can facilitate recognition of own kin.1.
- Laeng B et al (2006).
- Why do blue-eyed men prefer women with the same eye color? (Behavioral Ecology and Sociobiology, DOI 10.1007/s00265-006-0266-1) Article is available to journalists as a pdf.
- Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
: Blue eyes – A clue to paternity
How do babies get blue eyes?
Eye color changes over time – Iris color, just like hair and skin color, depends on a protein called melanin. We have specialized cells in our bodies called melanocytes whose job it is to go around secreting melanin. Over time, if melanocytes only secrete a little melanin, your baby will have blue eyes.
- If they secrete a bit more, his eyes will look green or hazel,
- When melanocytes get really busy, eyes look brown (the most common eye color), and in some cases they may appear very dark indeed.
- Because it takes about a year for melanocytes to finish their work it can be a dicey business calling eye color before the baby’s first birthday.
The color change does slow down some after the first 6 months of life, but there can be plenty of change left at that point. Eye color is a genetic property, but it’s not quite as cut-and-dried as you might have learned in biology class.
Two blue-eyed parents are very likely to have a blue-eyed child, but it won’t happen every single time. Two brown-eyed parents are likely (but not guaranteed) to have a child with brown eyes. If you notice one of the grandparents has blue eyes, the chances of having a blue-eyed baby go up a bit. If one parent has brown eyes and the other has blue eyes, odds are about even on eye color. If your child has one brown eye and one blue eye, bring it to your doctor’s attention; he probably has a rare genetic condition called Waardenburg syndrome.
What are the odds of two brown eyes make blue?
Improve your fertility and get pregnant faster – Obie is your reproductive health coach, helping you reach your goal with expert personalized guidance. Download app Not an iOS user? Sign up to be the first to know about Obie for Android. Sign up to get pregnancy alerts and updates on your baby’s development.
If both of you have brown eyes, then there is generally a 25% chance that the baby will have blue eyes if both of you carry the recessive blue-eye gene. But if only one of you has a recessive blue-eye gene, and the other has two brown, dominant genes, then there is a less than 1% chance of the baby having blue eyes.
Each person carries two copies of every gene, one copy inherited from mom and one inherited from dad. Homozygous means that the two copies match (for example, maybe both copies are for brown eyes). If someone is heterozygous, it means that the two copies of the gene differ (for example, one for brown and one for non-brown).
What if both parents have brown eyes?
What color eyes will my child have? – There’s no guarantee when it comes to your offspring’s eye color. While a baby inherits half of their eye color genetics from one parent and half from the other parent, the way that the genes interact also plays a role in determining eye color.
Differences in eye color are also influenced by differing amounts of melanin, the pigment responsible for eye color (plus hair color and skin tone). For instance, many white non-Hispanic babies are born with blue eyes because they don’t have the full amount of melanin present in their irises at birth.
As the child grows older, if they’ve developed slightly more melanin in their irises, the eyes will be green or hazel, When the iris stores a lot of melanin, the eyes will be amber (a golden brown), light brown or dark brown. Even though you don’t know the amount of melanin your baby will have, you can still get a pretty good sense of eye color from the parents’ eye colors.
Two blue-eyed parents are likely to have a blue-eyed child, but it’s not guaranteed. Two brown-eyed parents are likely to have a brown-eyed child. Again, it’s not guaranteed. Two green-eyed parents are likely to have a green-eyed child, although there are exceptions. Two hazel-eyed parents are likely to have a hazel-eyed child, although a different eye color could emerge. If one of the grandparents has blue eyes, the odds of having a baby with blue eyes increases slightly. If one parent has brown eyes and the other has blue eyes, the chances of having a brown-eyed or blue-eyed baby are roughly even.
The Fertility Institutes, which offers fertility services in California, New York, Utah and Mexico, offers the following odds of a baby’s eye color based on the parents’ eye colors. (Due to rounding, percentages don’t always add up to 100%.)
Both parents with brown eyes: 75% chance of baby with brown eyes, 18.8% chance of baby with green eyes, 6.3% chance of baby with blue eyes. Both parents with blue eyes: 99% chance of baby with blue eyes, 1% chance of baby with green eyes, 0% chance of baby with brown eyes. Both parents with green eyes: 75% chance of baby with green eyes, 25% of baby with blue eyes, 0% chance of baby with brown eyes. One parent with brown eyes and one parent with blue eyes: 50% chance of baby with brown eyes, 50% chance of baby with blue eyes, 0% chance of baby with green eyes. One parent with brown eyes and one parent with green eyes: 50% chance of baby with brown eyes, 37.5% chance of baby with green eyes, 12.5% chance of baby with blue eyes. One parent with blue eyes and one parent with green eyes: 50% of chance of baby with blue eyes, 50% chance of baby with green eyes, 0% chance of baby with brown eyes.
Keep in mind that it may take six to 12 months for a baby’s true eye color to emerge, so the color you see at birth can certainly change. SEE RELATED: Is it true all babies are born with blue eyes?
Are brown eyes dominant to blue?
Why are our kids’ eyes different colours? – Let’s look at why a blue-eyed parent (dad) and a brown-eyed parent (mum) and can have brown, green, and blue-eyed children. For gene 1, OCA2, there are two possibilities: brown or blue. The brown version of gene 1 is dominant over the blue one. Dominant means that if at least 1 of your two copies is brown (Bb), then you will have brown eyes. Geneticists represent the different versions of the eye colour gene as B for brown and b for blue (the capital letter is the dominant, the lowercase, recessive).
- So brown eyes are either Bb or BB and blue eyes are bb.
- For gene 2, there are two possibilities, green or blue.
- Green is dominant over blue.
- Green eyes can be GG, or Gb, while blue eyes are bb.
- Brown is dominant over green, so if you have a B version of gene 1 and a G version of gene 2, you will have brown eyes.
The possible gene combinations that can give you brown, green, or blue eyes are shown in the chart. Back to the green or blue-eyed children. Dad can only be bb bb as he has blue eyes. Since mum has brown eyes, she could have any of six different possibilities.
What if one parent has blue eyes and the other brown?
For example, if a mother has two blue-eye genes and a father has two brown-eye genes then each child inherits a brown-eye gene from their father and a blue-eye gene from their mother. The brown-eye gene is dominant and overrides the blue-eye gene, so all the children have brown eyes.