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Q: GENETICS ( Answered 5 out of 5 stars,   9 Comments )
Category: Health > Children
Asked by: albanov-ga
List Price: $5.00
Posted: 20 Nov 2002 17:19 PST
Expires: 20 Dec 2002 17:19 PST
Question ID: 111606
Subject: Re: GENETICS
Answered By: skermit-ga on 20 Nov 2002 17:42 PST
Rated:5 out of 5 stars

Yes, according to the relationship between recessive and dominant
genes, it's not uncommon for two brown eyed parents to have a blue
eyed child (if they both carry the recessive blue eyed gene) and/or
two blue eyed parents having a child with brown eyes. I quote from a
kid's page on recombination or gene shuffling (which is linked below):

"...two brown eyed parents having a blue eyed child would happen less
often than two blue eyed parents having a brown eyed child, unless the
blue eyed couple has no one in their family with brown eyes"

The parents with blue eyes have to possess the brown eyed gene meaning
their parents or higher up have to have at least one person with brown
eyes (somewhere up the line). Below is some information on your
specific case, and also how to determine the probability given the
known genes of the parents using Punnett squares. Use the eye color
calculator to find out the specifics for a test case. Glad to have

Search Strategy:

Additional Links:

Godlessheathen's kids page on evolution 2:

Eye color calculator:

Primer on Punnett Squares:

Thank you for the opportunity to answer your question, if you require
more information, please clarify the question, or if you find this
answer satisfactory, please feel free to rate it. Thank you!


Clarification of Answer by skermit-ga on 20 Nov 2002 17:48 PST
Oops... I forgot the search strategy, so here it is.

Search Strategy:

parents blue eyes brown eyes on google:

eye color punnett square on google:

albanov-ga rated this answer:5 out of 5 stars

Subject: Re: GENETICS
From: ac67-ga on 21 Nov 2002 06:37 PST
Funny how the second link cited in the answer actually contradicts the
answer. The first link actually is wrong. Ordinarily, as the brown
gene is dominant, if you have even one brown gene the eyes would be
brown.  Therefore two blue eyed parents cannot have any brown genes to
pass on to the child (or their eyes would be brown, not blue). 
However, there may be unusual circumstances where a parent has a gene
that is not expressed for some reason. I'm not sure if this applies to
eye color genes or not, but it might.  Another explanation could be a
mutation. The brown gene may spontaneously appear as a new mutation in
the child, when it is not present in either parent.
Subject: Re: GENETICS
From: surgeon-ga on 21 Nov 2002 09:50 PST
the answer given by the researcher is WRONG. Blue is a recessive gene;
meaning that to have blue eyes you have to have two blue genes in your
makeup. So blue-eyed parents would have only blue genes, and could
produce only blue-eyed babies. Brown is dominant, so to have brown
eyes, you need only one brown gene; so a brown parent could carry a
blue gene and pass it on half the time. If the other brown parent had
the same makeup, then one out of four of their children could be blue.
But not the other way around....
Subject: Re: GENETICS
From: skermit-ga on 21 Nov 2002 10:23 PST
Guys, from the answers I gave, especially the 2nd link, they state
it's not only two genes that control eye color, just what to expect
not what's possible. From an Ann Lander's question (linked below):

Dear Nanuet: Tell your mother to stop worrying about nonsense.
According to the experts in the field of genetics, eye color can come
from more than one gene. Some shades of brown are the result of
pigment that can come from parents with any color eyes. While not
common, it is entirely possible for blue-eyed parents to have hazel
brown-eyed children.

So guys... chill please. It's more complicated than just the two
parents, it takes into account the grandparents and also other genes
which may/may not be discovered/identified yet.

Additional Links:

Ann Lander's question:

Subject: Re: GENETICS
From: sgtcory-ga on 21 Nov 2002 10:58 PST

This is SgtCory, a research colleague (with Skermit)

Skermit is correct in his findings. While the people posting comments
are correct in much of what they said - they don't have the commodity
of tons of fresh research sources at their fingertips. Here is what I
found to confirm Skermits findings for you:

Excerpt from Oregon State University
"Yes it is possible.  Eye color inheritance is not as simple as was
once thought but brown eyes are dominant over blue eyes.  This means
that the child's parents and grandparents were probably heterozygous

Excerpt from Dr. Sokal-Gutierrez
"So your and your partner’s brown eyes could have resulted from
receiving either brown eye genes from both parents or brown from one
and blue from the other.... But it’s also possible that they got blue
eyes, if both of you handed down a blue gene."

Color Genetics
"Therefore, two parents both of whom have brown eyes can produce a
child with blue eyes, if they both carry a hidden blue-eye gene within
their gene pair..."

College of Education Alabama
"...their must be mutations on BOTH the male sperm and egg of the
zygote where the recessive gene for blue eyes is located.  That's why
it is rare for this to happen."

Hope that helps clarify that Skermit is indeed correct. Genetics is
not one of the areas that we can *trust what we know*. The latest
information will usually be most accurate.
Subject: Re: GENETICS
From: sgtcory-ga on 21 Nov 2002 11:04 PST
Notice most of the excerpts are about the "reverse order", but the
theory is fully explained on each page, and it works in numerous
diffenret scenarios to include yours. We are prohibited from copying
full text sources, so I pulled the closest comments.
Subject: Re: GENETICS
From: webadept-ga on 21 Nov 2002 11:49 PST
This question certainly shows the difference between the comment area
and a real Researchers. Good answer. I suppose it would be impossible
for two blue eyes to have a brown eye as a child, if only the eyes
were mating, but there is bit more involved in gene makeup than just
the eye color. Good to see the Researchers operate on a higher level
than high-school biology.
Subject: Re: GENETICS
From: surgeon-ga on 21 Nov 2002 16:41 PST
most of the citations refer to brown eyed parents and blue eyed
children. In reference to each parent having a mutation in their blue
eye genes, of course any thing is possible. The odds are extremely
low. And if one is loose in defining "brown" it becomes more possible.
A dark brown child from two blue parents is very unlikely. Insults
Subject: Re: GENETICS
From: ac67-ga on 25 Nov 2002 12:25 PST
In my comment, I did not state the researcher was wrong.  In fact I
agree with his conclusion but feel he chose poor material to support
it.  In particular, I stated: 1) the second website contradicts his
answer, which it does - if you put in 2 blue eyed parents into the
calculator, it does not show any possibility of a brown eyed child. 
2)  The first website listed is also wrong, given this quote, "Since
brown eye genes are dominant over blue eye genes, two brown eyed
parents having a blue eyed child would happen less often than two blue
eyed parents having a brown eyed child, unless the blue eyed couple
has no one in their family with brown eyes"  If it were as simple as
one dominant (brown) and one recessive (blue) gene, then two blue eyed
parents would never have a brown eyed child, so this quote is wrong. 
I then went on to give a couple (but by no means all) examples that
might explain the brown eyed child.  Although the "researcher" was
correct in his answer, his explanation and support left a lot to be
Subject: Re: GENETICS
From: sgtcory-ga on 26 Nov 2002 07:09 PST
I don't think it left alot to be desired at all, and I am sure the
comments were more directed towards surgeon. Your comments were rather
constructive, whereas surgeon blatantly stated :

"the answer given by the researcher is WRONG" 

He later changed his comments to this:

"odds are extremely low" - So it can hapen right?

With regards to your findings, here another angle to consider :

The second link is indeed a correct reference. We just need to read
the whole thing, and not look at just the software. Here is what the
site says about the software :

"Note that this two gene model does not explain most human eye color
inheritance..... Human eye color inheritance is a complicated
polygenic system than we are pretending in this simplified two gene

The keyword here is pretending. It's 'hypothetical' software. lol

The second resource was also correct. Again we just need to read the
sentences :

"parents having a blue eyed child would happen less often than two
blue eyed parents having a brown eyed child"

The keywords in this reference are "would happen less often than two
blue eyed parents". This implies that the possibility does exist.

This answer definitely delivers a resounding 'yes' to the question at
hand, which was :


The asker didn't want statistics, rather wanted to know if it was
possible. The answer was based on the fact that a possibility existed,
rather than the genetic process involved.

Good job skermit!


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