Blonde hair and hazel eyes...

[lovethelook1]

hmm, interesting post

hey everyone

in reply to the last message, my sister has two different coloured eyes

she has one blue and one brown and she has since she was born

my two brothers both have brown eyes and i have a hazel greeny color.

really i don't know how she got such a drastic look when both my parents have brown eyes..???

[Edtharan]

There is a phenomina called Chimerism (spelling?), where you have 2 different geno types expressed in the one body. There are several way to reach this ranging from fraternal twins that merged dureing early gestation the two different genese expressing in differnt areas of the body.

 

I have heard of more servere chimmerism where the skin colour in differnt patches on the body can be noticeably different (and apparently it is more common in women than men - and more common than you think). I even have heard of people having two distinct sets of genes in differnt parts of thier boddies (that is if you took a sample of genetic material from one part of the body it would be different to that from another part of the body).

[Dak]

There is a phenomina called Chimerism (spelling?)' date=' where you have 2 different geno types expressed in the one body. There are several way to reach this ranging from fraternal twins that merged dureing early gestation the two different genese expressing in differnt areas of the body.

 

I have heard of more servere chimmerism where the skin colour in differnt patches on the body can be noticeably different (and apparently it is more common in women than men - and more common than you think). I even have heard of people having two distinct sets of genes in differnt parts of thier boddies (that is if you took a sample of genetic material from one part of the body it would be different to that from another part of the body).[/quote']

 

 

The 'more common in women' bit is actually down to the X chromosomes. the amount of gene product is proportional to the amount of genes present in many cases (i.e. two alleles = twice as much protien as there would be if just one alleles was present).

 

This presents a problem with the X-chromosome, as the Y-chromosome is virtually empty, with few alleles present.

 

so... if an allele on the X chromosome only made half the neccesary amount of protien, men -- with only one X chromosome and so only one allele -- would only make half as much protien as neccesary, and would be screwed.

 

If an allele on the X chromosome makes 100% of the neccesary amount of protiens, then women -- with two X-chromosomes -- would make twice as much protiens as neccesary, and would be screwed.

 

The way that this is solved is that alleles on the x chromosome make 100% of the neccesary amount of protien (so men are OK), and if more than one x chromosome is present, one of them will condense and become inactive, so women end up with only one functional x-chromosome (so women are ok too).

 

now... the initial zygote will replicate a few times, and then each of the stem-cells will randomly deactivate one of the x-chromosomes. each of the offspring cells from this stem-cell will have the same x-chromosome deactivated. this results in patches of cells that have the maternal x-chromosome deactivated, and patches that have the paternal x-chromosome deactivated.

 

the relevence being that if, say, thir are two alleles stored on the two x-chromosomes that have obviousely different phoenotypic effects, the result will be a 'patchy' female (such as the skin colour patches that you mentioned).

 

so... this (i.e. the chimerism that is more common in females) isn't chimerisism of the 'two completely different genomes' variety, which, afaik, isn't any more common in females than in males.

 

the x-chromosome inactivation can't result in the hair/eye colour gubbins as the genes are located off of the sex chromosomes, but i thought it was interesting anyway.

[Edtharan]

so... this (i.e. the chimerism that is more common in females) isn't chimerisism of the 'two completely different genomes' variety, which, afaik, isn't any more common in females than in males.

Yeah, it is not the same as two distinct cell lines, but as far as I know it is still called chimerism.

 

Actually, in women cells from a baby will enter the mother and remain there for the rest of her life and function as they were intended. This makes all Mothers, Chimeres. This is because during pregnancy, cells from the foetus will cross the placenta. The mother has a suppressed immune system (otherwise it would attack the foetus and cause a misscariage), and this allows the cells to survive. Even after pregnacy these cells seem to still be accepted by the mother without rejection.

[GutZ]

until I was about 6' date=' then my hair started to darken. By the time I was in high school, it was "paper bag brown" . It was also really oily and always looked dirty. I started "frosting it" to improve the color and also to dry it out some. I was ever so glad when foiling was invented. It was torture to have long hair pulled through a cap with crochet hooks.

 

Cut to the chase - I was born blonde with hazel eyes.[/quote']

 

Same with me I was totally blond till I was like 10 or so, but now...The dirty look.

[Bluenoise]

No, its just the nature of probability. It works with flipped coins as well. Actually, both zeroth and sorcerer are right, they are just saying different things. (I think)

 

Actually your probably shouldn't tell someone their wrong if you don't know the answer yourself.

 

The genes are linked being placed in close proximity of each other on their chromosome. They're not the same gene, eventhough both code for a melanin modifying/producing protein. Melanins are actually fairly complex widley varying irregular molecules. They are produced from different combinations of different subunits in different amounts. Thus there is a wide array of genes that code for the proteins required to produce them. So not only do the genes matter but so does the level of expression etc.

 

Like their might be a gene that leads to what we recognize as blue eyes, but as you'll notice there are many different types of blue, brown etc eyes. This gets even more complicated for skin colour.

 

Many people seem to believe skin colour is due to the level of melanin, which they consider as a regular molecule. But the truth is far more complex. You can have different shades at different or the same intensity.

[mr affy]

sorry, im finding all of this very confusing...

 

in short, does anyone know the rarest genetic combinations for eyes/hair in order or anything?

[ardith]

Hi! I read somewhere that some rare combinations are red hair with brown eyes, red hair with green eyes, blonde hair with brown eyes, and black hair with green eyes. I've also heard that only about 2% of the population has green eyes....so it's one of the rarest eye colors. I wonder if that's true though? I seem to know a lot of people with them, myself included!

[megabear14]

Hello people I have to say, I have natural blonde hair and hazel eyes. I dont think its weird. It just makes me one of a kind (:

[toastywombel]

Hello people I have to say, I have natural blonde hair and hazel eyes. I dont think its weird. It just makes me one of a kind (:

 

Correction it makes you two of a kind, I as well have blonde hair and hazel eyes.

[SH3RL0CK]

Correction it makes you two of a kind, I as well have blonde hair and hazel eyes.

 

Three of a kind...don't forget the original poster

[alexx_2010]

Because you are blond that does not mean that you must have hazel eyes,

I have hazel eyes with dark hair.

Organic Makeup

[Rugabee]

Hey guys happy you discussing this, I have notice than from all my friends that recently had kids, where one of the parents have brown eyes and the other blue eyes, the kids all have BLUE EYES, as you know Bb (B=Brown, b=blue) Brown is a dominant gene and in general most of them should have brown eyes. Has anyone else notice this?

 

It helps to if you use a Punnett Square to fine the probability of the features that will show up in a kid. With your friends it was a 50% of the kids having brown and 50% having blue.