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Archiver > GENEALOGY-DNA > 2006-05 > 1147113977


From: "Ken Nordtvedt" <>
Subject: Re: [DNA] Brown eyes
Date: Mon, 8 May 2006 12:46:17 -0600
References: <B5B131F8D0AFA34BBCBEC64AC6C3E18833FD99@echqexc01.elections.ca>


That's covered by the standard Mendelian rules of a dominant gene, and is,
in fact, part of the case of my family's situation.

two brown genes = brown eyes
one brown gene = brown eyes
no brown gene = non-brown eyes (many different possible shades of blue,
green, grey, ..... "Complex" interaction of more than one gene as the list
will remind us.)

We get a copy of a particular gene from each parent. If we end up with two
brown genes, we can only pass on a brown gene to our children, so their eyes
will be brown except for the less than one percent of the cases where
another "epistatic" gene can suppress the expression of the dominant brown
gene.

But my father had a blue eyed father and brown eyed mother. My Dad had
brown eyes, so he got a brown gene from his mother plus a blue gene for sure
from his father who only had blue genes (assuming no epistatic rare event).

My mother had blue eyes, hence no brown genes (assuming no epistatic rare
event). So I and my two siblings each had a 50/50 chance of brown eyes. We
always got a blue gene from our mother (because she necessarily has two),
and we had equal chance of getting father's blue gene or brown gene

In fact, I and one sibling has brown eyes, while the other sibling has blue
eyes.


----- Original Message -----
From: "Barron, Margaret" <>
To: <>
Sent: Monday, May 08, 2006 12:30 PM
Subject: RE: [DNA] Brown eyes


> What if both parents have brown eyes but the mother (most likely not the
> father as his entire family is Persian)carries the gene for blue/green
> eyes?
> My sister asked me this the other day, since she is getting married this
> summer and her fiance is from Iran (with a 100% Persian background). She
> has light brown eyes with a 'slightly hazel' tone to them. I have 'bright'
> green-blue eyes (everyone always thinks I'm wearing contacts). Our mother
> has light green eyes (like fresh grren grass) and our father has dark
> brown eyes. She asked what her chances are of having a child with
> non-brown/hazel eyes.
>
> Maggie Barron
> Ottawa
>
> -----Original Message-----
> From: John Lerch [mailto:]
> Sent: May 8, 2006 1:58 PM
> To:
> Subject: [DNA] Brown eyes
>
>
> It seems as if there is one gene that is indeed dominant for brown
> eyes--if you've got it, you're brown-eyed and there is no problem with
> your having a blue-eyed child, since you could be heterozygous; but
> there are many degrees of brownness, from near hazel to almost black.
> As a consequence, I've had no problem with citations that two blue eyed
> people can indeed have a brown eyed child. I take that to mean just
> barely brown eyed--on the verge of hazel--not the per.......ity eyes
> that someone complimented my daughter on once. (Don't recall the
> southern expression for that variety of sparkling brown.)
>
> Ken wrote
>
>> Surprisingly, Glen and I agree on this point.
>>
>> If listers explore the archives, you'll find quite a
>> few threads from the past both on skin, hair and eye
>> color. Eye color in particular is an incredibly
>> complex autosomal trait and the genetic studies are
>> difficult to plod through.
>
>
> On the contrary, the basic bifurcation of eye coloring between brown and
> non-brown is quite simple, controled by one dominant brown gene.
>
>
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