Can Two Parents Brown Eyes Have Baby Blue

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How can dark-brown-eyed parents have blueish-eyed children?

• Thread starter Pithikos
• Offset date Mar 6, 2013

I am learning about genes and heritage currently and I am a bit baffled virtually something.

In my volume information technology states that in a plant's gene, if S is for polish leaves and s for rough leaves, then we get these combinations:

                          Parent institute | Kid plant | Ascendant alleles S + s       ->     Ss     ->     S southward + S       ->     sS     ->     Due south S + Due south       ->     SS     ->     S s + south       ->     ss     ->     southward                        

So the only style to get a plant with polish leaves is if both parents have the recessive factor south.

Merely what happens when it comes to eye colour? If we say that for brown eyes nosotros take B and for blueish eyes we accept b then how tin can we get bluish eyed children from brown eyed parents? For case:

                          Parent      |    Kid     |  Dominant alleles B + b      ->     Bb      ->     B b + B      ->     bB      ->     B B + B      ->     BB      ->     B b + b      ->     bb      ->     b                        

And then the only way for a kid to become bluish eyes is the two parents have blueish optics, according to my tabular array. In any other case the kid has brownish eyes.

This ofcourse is wrong as I know families where the parents accept brownish eyes and some of their children have blue eyes. So where did I practise wrong?

Answers and Replies

Each parent has two alleles, with the brown eyed B dominant, not just one as in your tabular array. And so the way brown-eyed parents accept a blue-eyed kid is as follows:

Mother - Bb Father Bb Possible Children BB, Bb, bB, bb

The bb combination will take blue optics. Tin blue-eyed parents have a brown-eyed child?

Annotation that eye colour isn't only determined past one gene. In elementary models information technology tin can exist represented by ii genes: 1 governing chocolate-brown/bluish and one green/blueish with dominance being a bureaucracy of dark-brown > green > blue but in reality it's more than complicated than that. At that place are a wide multifariousness of genes involved in the germination of the middle that dictate middle colour.

Fascinating, I never realised that blue eyes were a event of Rayleigh scattering of reflected lite.

Fascinating indeed! I too oftentimes think of that couple by the Black Sea 6000 years ago when they first looked in to their newborn baby boys blue eyes and what they would have idea of his and their 1.2 billion direct descendants? Depending were in the earth y'all are they seem to be getting rarer. But here in Ireland were there has been little immigration for over 2000 years bluish eyes make up 96% of the population!

I too often call back of that couple by the Black Sea 6000 years agone when they first looked in to their newborn baby boys blue optics and what they would have idea

What is surprising in the newborn having bluish eyes? They all do, eye color changes much later.

What is surprising in the newborn having blue optics? They all do, eye colour changes much afterward.

All of them!!! Nigh Jewish people of Kazakh/Ashkenazi decent such equally myself are born with dark chocolate-brown or even black eyes. Not to mention nigh African races south of the Sahara. Newborn brown eyes also occur amidst native Americans/Asians/Hispanics. And yep fifty-fiftywhite Europeans occasionally!!

That's good to know, I didn't know that could happen

It is good to know Monique, there are so many superstitions and sometime wives tales when it comes to eye colour!

It is considering is a Mendelian trait; if both parents accept the b gene, even if they are brown eyed they may have blue-eyed children, every bit it is recessive. Equally far as I remember, the percentages are: 25% chocolate-brown eyed children, 50% Bb, and 25% bb, that is, blue eyed children.

Each parent has two alleles, with the brown eyed B dominant, not just one as in your table. And so the way brown-eyed parents accept a blue-eyed child is as follows:

Mother - Bb Begetter Bb Possible Children BB, Bb, bB, bb

The bb combination will have blue eyes. Can blue-eyed parents take a brown-eyed child?

Ok, but if each parent has ii alleles, then we accept a total of four. How are only two alleles chosen from those four for the child? Is it a random choice?

Ok, but if each parent has 2 alleles, and then we take a total of 4. How are only two alleles called from those 4 for the child? Is it a random option?

One allele is on each chromosome and each parent gives their child one chromosome. It'southward a bit more than complicated than that simply is this what you're asking?

Ok. I accept a question though it appears it'south a couple years after your discussion. lol.

my wife thinks she might be adopted just her parents aren't talking to her right at present and take motive to possibly lie. Here is our situation.
Me/Dad: Brown eyes. Mom has brown optics, dad, his mother and her mother have blue.
Her/Mom(my married woman): Brown eyes. 6 siblings have brown optics. Mom and Dad and their respective moms and dad ALL have brown eyes. Here cousins ALL accept dark-brown eyes.
We have two kids, a boy and girl. Both with blue optics. Is this possible if she'southward really genetically from people with brown eyed parents and grandparents?

Ok. I have a question though it appears it's a couple years after your discussion. lol.

my wife thinks she might be adopted but her parents aren't talking to her right now and take motive to mayhap prevarication. Hither is our situation.
Me/Dad: Brownish eyes. Mom has dark-brown eyes, dad, his mother and her mother accept bluish.
Her/Mom(my wife): Brown optics. Six siblings have dark-brown eyes. Mom and Dad and their corresponding moms and dad ALL have brown optics. Here cousins ALL have chocolate-brown eyes.
Nosotros have two kids, a boy and girl. Both with blue eyes. Is this possible if she's actually genetically from people with brown eyed parents and grandparents?

Two brownish eyed people tin can take babies with blue optics.

The short answer is that dark-brown-eyed parents can have kids with brown, bluish or well-nigh whatever other color optics. Eye colour is very complicated and involves many genes.

http://genetics.thetech.org/ask/ask2

My ex fiancee is Sicilian, his parents had dark dark-brown pilus and eyes, he has sky blueish eyes and had blond hair until his teens when it turned browner. He believes he may have Norman beginnings. Sounds reasonable, he's as well very stake.

Last edited: Apr 15, 2015

And so the gene leading to blue optics can be 'recessive' for several generations, not just ane or ii?

The gene(and information technology isn't simply one cistron, and it isn't only genes) doesn't know or care near how many generation, or the colour of the parents. If it is at that place, it is there.

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