Brown eyes?

N

NoUserNameSpecified

Registered Member
I heard that brown is the dominant eye color which makes me wonder about something. In my family, in the past five generations (on both sides) only two people have had brown eyes out of twenty four. The rest were either blue, green, blue/green mix and I have green/gray mixed eyes. If brown is the dominant eye color than why such a small presence of it in my family? Does anyone know of any other cases like this? Is there any significance to it at all?

If youre wondering how I would know the eye color of five generations back, its actually three generations back. I am counting my generation as one and my sisters baby as another, so parents are three and then grand parents and great grandparents.
 
I remember reading about something similar to that in my biology textbook a couple years ago. It talked about how widow's peaks are dominant, but the percentage of people who have widow's peaks remains lower than that of people without widow's peaks. It explained why that was, but I don't remember it. I don't remember much biology, unfortunately. :(

Sorry I couldn't help. I too would like to know the answer to this.

By the way . . . I have brown eyes.
 
Well, you have an entirely too small sample population, and all your samples are related. Blue eyed parents can only give birth to blue children, as blue eyes are the phenotype of two recessive genes.

Also, blue-eyed people are often identified with certain ethnic groups, and as long as your family remains within a certain ethnic group, your chance of marrying heterozygote brown eyed people increases, as does the chance of marrying blue eyed people.

Of course, since it's pretty appearant you don't know Mendelian genetics, you probably won't be able to see what I'm blathering about.
Lo siento, chicos.
 
First -- multiple genes control things like eye color. It doesn't matter what the color is, whats important is that the genes which cause green/blue/whatever are..how shall I put it..'in control'. Brown eye genes are (probably) there, but they're not being expressed because they're overpowered right now.

Like Roman said, you really need to learn a bit of Mendelian genetics for it to make sense. What might look like an anomaly on the surface.. like eye color.. actually makes perfect sense once you understand the innerworkings. The technical term is 'epistasis'

http://www.ndsu.nodak.edu/instruct/mcclean/plsc431/mendel/mendel6.htm
For this type of pathway a functional enzyme A or B can produce a product from a common precursor. The product gives color to the wheat kernel. Therefore, only one dominant allele at either of the two loci is required to generate the product.

Thus, if a pure line wheat plant with a colored kernel (genotype = AABB) is crossed to plant with white kernels (genotype = aabb) and the resulting F1 plants are selfed, a modification of the dihybrid 9:3:3:1 ratio will be produced. The following table provides a biochemical explanation for the 15:1 ratio.
Click to expand...
(kinda similar to your 24:2 ratio, eh?)

Basic genetics is extremely interesting subject to read up on if you haven't already..
 
Xerxes is right, there's a heap of genes controlling eye color, and it's actually really quite complicated.
 
in simple form, given the choice, brown will dominate over another colour, its not enoughm to have your great grandma on one sides genes, although eye colour does occur thru long passed on genes sometimes
 
If brown is the dominant eye color than why such a small presence of it in my family? Does anyone know of any other cases like this? Is there any significance to it at all?
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Like it or not, it also has something to do with social eugenics.

Blue eyes are regarded as superior to brown eyes.
There are blue-eyed people who reject brown-eyed people on principle.

In your family, your ancestors were probably such blue-eyed snobs who chose only blue-eyed people as spouses, hence the dominance of blue eyes in the family.


No pun intended, but people do often act on what seems to be merely a whim.
 
Obviously, the original poster does not acknowledge that eye colour is hereditary and if he had even the slightest scientific background would also recognise that green is the best eye colour. :)
 
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There's an important distinction between a particular gene being dominant and that gene being more common than its competitors.

Black eyes are dominant in dogs. (I'm going with the simplified genetic model originally posted, there's no need to complicate things to make the point.) But in certain breeds, blue eyes are considered the breed standard so whenever a breeder gets a litter with black eyes he'll take the whole bloodline out of the gene pool and neuter every living member of it he can get his hands on. (Well, a responsible breeder will do that. There are a few of us left.)

So the population of that breed has no black-eyed genes, therefore it doesn't matter if they're dominant. The recessive blue-eyed genes have no competition.
 
Everyone seems to be disregarding something.
The Mailman.
Yes, it sounds like a joke, but the reality is, some members of the flock just may have strayed.
 
water said:
Like it or not, it also has something to do with social eugenics.

Blue eyes are regarded as superior to brown eyes.
There are blue-eyed people who reject brown-eyed people on principle.

.
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Pigmentation in general is what we call multi-genic - as somebody said (sorry -can't remember who) lot's of genes interact to control eye and hair colour. We have as yet no reliable model for that

As a possibly interesting aside: the characteristics that we notice most readily - stature, hair and eye colour, intelligence, personality etc. are the least well understood in genetics

And no - when it comes to muli-genic inheritence, Mendel doesn't really help. He gives us the rules for simple 2-gene systems, from which we can extrapolate to some extent

But the rest - most of it - requires some quite sophisticated mathematical modelling
 
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