I agree with Scole, my parents both have brown eyes and I have two sisters with blue eyes.
Just like Tammy said, I agree with Scole:
What I’d forgotten (or flat out didn’t know) was that Mendel grew several generations of peas before deciding which traits to use in his experiments. He omitted traits that would not give clear cut results.
Now we know (from biology texts, like the one I just finished reading) that some traits are polygenetic or governed by multiple alleles at several different gene loci.
This text went on to say that most human traits are polygenic and included this list: skin color, height, shape, metabolic rate, behavior…
But it was head-banging reading and that must be why biologists haven’t jumped right in here to explain this - explaining must be double time head-banging.
…
Taking a left turn here - there is another phenonomen called pleiotrophy the examples had to do with white cats:
White coat cat blue eyes = deaf
White coat cat 1 blue eye = deaf on blue side
1 orange eye = hearing on orange side
The text is: Biology, by Curtis and Barnes, pub by Worth Publishers, Inc. 1989.
Oh, I’m gonna keep using these #%@&* codes 'til I get 'em right.
I think I see the point here. I have no children; but my sister, who has brown eyes, same as I do, has two children, by her husband, who has blue eyes. Both children also have blue eyes, and both were blond as children. My sister sure wasn’t blond as a child; whether her husband was I don’t know; they’ve long since split up.
absolutely possible. i have blue eyes which are the product of a pair of recessive genes… which means that i inherited the blue eye gene from both of my parents. this doesn’t necessarily mean that my parents have blue eyes, but just that they carry the gene. say for instance that the gene for blue eyes is b and the gene for brown is B. if my parents have brown eyes their gene pairs could be, Bb or BB. and since B is the dominant gene, it only takes one. the possible gene pairs are for a couple with Bb gene pairs are, Bb, BB, Bb, and bb. so there’s a 1/4 chance the child will have blue eyes as it takes two recessive genes to overcome one dominant.
“human beings, vegetables, or cosmic dust; we all dance to a mysterious tune, intoned in the distance by an invisible piper.” - albert einstein
Bear in mind that we may be discussing two seperate types of eye color.
First, there is the eye color that you see when you look.
Second, there is the genetic eye color.
There are only two possible genetic eye colors: Blue and Brown.
Genetic blues are a pure “collodial” blue (their color comes from the colloidial bodies floating around in the clear fluid. A similar effect causes the sky to appear blue.)
Genetic browns are everything else–grey, green, brown, black, hazel, AND various shades of blue.
Two people with obviously brown eyes can have a child with eyes that APPEAR blue, but which are, in fact, genetically brown.
Two people with genetically blue eyes cannot have a child with brown eyes, because to have genetically blue eyes, all of the “blue genes” must be present and dominant in both parents. If it is otherwise, their eyes are genetically brown, no matter how blue they may appear.
-David
soulfrost - i’m totally not getting this, shouldn’t genetically brown eyes appear, say… brown? it makes absolutely no sense to me… and besides that, when i was in biology and whenever this was brought up with somebody else who had taken it in school or what have you… it’s said that the gene for blue eyes is also the gene for green and grey, whereas the brown gene is the one that also causes hazel and black.
but blue eyes as the cause of a brown gene? it just doesn’t make sense…
oh. and one more thing… soulfrost, you say that there’s two gene’s. a blue and a brown… but the brown may cause shades of blue. but all a shade is, is a gradiation of light… so it’s still gonna be blue, no matter what shade of blue it is. and when you look at it this way it seems as though the chances of inheriting blue eyes would be much more likely, since the brown eyed gene holds that possibility, and the blue holds none other than that possibility. it just doens’t make sense to me… maybe i’m missing something. if so, feel free to straighten me out.
Ok, look at it this way:
BB=Blue
Bb=Brown
bB=Brown
bb=Brown
The information I posted earlier came from my Junior and Senior year Anatomy professor, who is a Geneticist, so I believe him. Eye color is one of his “pet peeves”, so we quickly learned that by asking about it, he would go on long tirades that would allow us to nap through most of the class.
Who decided that there are only two eye colors? Dunno. He DID mention that the two colors are not “Blue” and “Brown” but “Blue” and “Non-Blue”, but most people just use “Blue/Brown” unless they’re publishing.
Maybe that clears it up a bit: Blue = perfectly blue (BB), Non-Blue = everything else.
And yes, even eyes that appear blue can be genetically Non-blue, much like mixing a few drops of black paint into a quart of blue paint will make the color “non-true-blue” or some such.
-David
so if what you’re saying is true, then a couple both having green eyes, could have a child with brown eyes? funny, i’ve never seen that.
you also said that it depends on whether their blue by genetics or just appear blue… but how does that make a difference? the answer would still be yes, would it not?
“human beings, vegetables, or cosmic dust; we all dance to a mysterious tune, intoned in the distance by an invisible piper.” - albert einstein
okay i did a little family research and came back with this.
my great grandparents on either side have all got very light blue eyes.
my grandparents on either side have all got very light blue eyes.
my dad has blue eyes, and my mom has green.
and then again, my brother and i have both very light blue eyes.
and because we know that a genetically blue eyed couple can not have a child with genetically brown eyes, which you say green is a part of, either my whole family tree has a brown gene that coincidently always shows up as light blue, or else green is part of the blue gene.
which seems more logical?
just for the record i’m not so persistant with this because i refuse to be wrong, because it’s not a possibilty i rule out… but rather because this is something i’ve never heard of before and would like to know which way it actually works
I know this is hard to read and you might go back to the site for references:
Eye color is likely to be a polygenic trait. The early view that blue is a simple recessive has been
repeatedly shown to be wrong by observation of brown-eyed offspring of 2 blue-eyed parents. My
monozygotic twin brother and I, brown-eyed, had blue-eyed parents and blue-eyed sibs. Blue-eyed
offspring from 2 brown-eyed parents is a more frequent finding. In some Norwegian families,
Gedde-Dahl (1981) found diffusely brown eyes or centrally brown eyes segregating as simple
dominant traits, symbolized BEY1. Possible linkage to Km (Inv) and to Co was found, suggesting
the order Jk–Km–BEY1–Co. (Co and Km are not measurably linked.) In a linkage study, Eiberg
et al. (1986) scored eye color in a questionnaire as purely blue, green, gray, brown, or ‘don’t know.’
The presence of brown areas or spots were also noted. For the purpose of linkage analysis, they
assumed 2 main loci: (1) a ‘green/blue’ locus (GEY) with a dominant allele for green and a recessive
allele for blue, and (2) a ‘brown/blue’ locus (BEY) with a dominant allele for brown and a recessive
for blue. Linkage of GEY with Lutheran and secretor (located on chromosome 19 at q13.1) was
found. They reported a lod score of 3.37 (theta = 0.0 for males and 0.07 for females) against
Lutheran and of 1.79 (at theta = 0.1 in males) against secretor, from observations largely in different
families. In the full report, Eiberg and Mohr (1987) reported a combined lod score of 9.19 for
linkage between GEY and the Lutheran-secretor systems. They also found evidence for linkage of
GEY to brown hair color (113750) with a lod score of 5.06.
Eiberg (1997) suspected that green eye color is heterogeneous (perhaps with more than 2 loci),
because he had observed families segregating with chromosome 19 and others not segregating with
chromosome 19.
SEE ALSO
Davenport and Davenport (1907) ; Rufer et al. (1970)
It’s just not as easy as it used to be.
Ok, after having a very brief chat with my old prof, the source of my argument so far, I have a few more things to offer:
-
There really isn’t a “Blue Gene”. The genes are mostly known as “colored” and “non-colored”, sometimes as “blue” and “non-blue”…“blue” and “brown” are the more accepted layman’s terms–though keep in mind that we’re talking about genetics on this level, NOT the appearance of the eye.
-
Only by having all of the non-colored genes can you have genetically blue eyes. This is because genetic blues have very little pigmentation–the blueness is caused by colloidial bodies. Everyone else is considered to have genetically brown, or non-blue (colored), eyes.
-
It’s possible to have most of the non-colored genes as well as a few colored ones. In this case, you are considered genetically brown-eyed, although your eyes will appear blue–this is most common in both very light and very dark blues. Carried further, and using the correct colored genes (each gene adds a different amount of pigmentation), greens and even purples will be evident. All or most of these genes are hereditary.
-
Folks with mostly colored genes will have darker eyes: grey, brown, and black.
Like I said, this is how he explained it to me. He is a bona-fide geneticist, so I trust him. It’s always possible, though, that I may be misinterpreting what he’s saying.
-David
I’d bet you aren’t misinterpreting anything!
I’ve been going through the search engines and either get the very simple Mendelian eye color story or something very much less than clear.
So let’s stick with your version! I’ll contact some bio/genetic/something grad. students and let you know if anything better/clearer comes along.
I bet you aren’t misinterpreting anything!
I’ve been going through the search engines and either get the very simple Mendelian eye color story or something very much less than clear.
So let’s stick with your version!
I’ll contact some bio/genetic/something grad. students and let you know if anything better/clearer comes along.
Two brown eyed people can have a blue eyed child if they both have a recessive blue gene. Two blue eyed people cannot have a brown eyed child because they only carry the recessive gene of blue eyes.
That would be helpful, Jois! Thanks.
Let’s get this thing cleared up–divorce lawyers stand to make a mint!
David
I just remembered a couple of related things that I wanted to ask about…
First:
My neice has the most beautiful green eyes…and around the outside of the iris is a thin ring of gold.
I’m assuming that the gold is actually a brown that is being reflected/refracted so that it appears gold, but I’m not sure.
Second:
The prof that I’ve mentioned before has had some serious eye problems (as a geneticist, this naturally led him to study the genetics of the eye, or so I assume.)
Early on, he had to have his eye “keyholed”, which is when part of the iris is sliced away. Eventually, the entire eye had to go.
Now, the gentleman has a fake eye. He likes to tell (in private) about how he kept an unruly class in line. One day, he popped the fake eye out, laid it on the table, and announced “I’m going to the Dean’s office, but I shall be keeping an eye on you.”
Is that possible? Can fake eyes be removed without muss, fuss, or pain?
Anyone offer any ideas?
-David
who explained to the gentleman that if he ever did that to MY class, he’d return to find us shooting marbles with it…
ooh ooh! i know this one!
yes, fake eyes can be popped right out, no problemo.
a friend of my grandparents had one and would do it all the time.
plus, i saw a documentary on a woman who had one. same thing. in and out, no problem.
i imagine that ease needs to be there because they have to wash them regularly.
i think they just stick their finger behind it and pop it out.
“human beings, vegetables, or cosmic dust; we all dance to a mysterious tune, intoned in the distance by an invisible piper.” - albert einstein