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Author Topic: Genetics of eye and hair colour  (Read 12133 times)

Offline stevierar

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Genetics of eye and hair colour
« on: 21/12/2003 15:35:29 »
Hello from Bournemouth on the South Coast of England!

I've been terribly bored today, and have found myself reading various bits and pieces about genetics (I only started by trying to find out some fingers for how common ginger hair was... yes, I was *very* bored).

But now I've come to the horrifying conclusion that I must be the offspring of the milkman, and a neighbour. I don't know if someone would like to explain the probabilities and such of this, purely because it facinates me;

Me;
Hair: Ginger and curly
Eyes: Green with yellow-specks

Mum;
Hair: Black/Brown and straight
Eyes: Brown

Dad;
Hair: More brown than ginger, straight
Eyes: Blue

And...

Mums' mum;
Hair: Brown and straight
Eyes: Brown

Mums' dad;
Hair: Black/brown and straight
Eyes: Blue

and I honestly have no idea about my Dads' parents, what with not seeing my dad ever (I have photographs). But hey!

Just quite interested here, as far as I know, brown is the dominent gene, the same with brown being the dominent hair gene, and straight hair being the dominent, um, hair-staightness-gene (correct me if I'm wrong!).

Hope you can provide some insight into this, and sorry if it's in the wrong place. I am purely a freak of nature, or should I get down the adoption agency?


 

Offline Ylide

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Re: Genetics of eye and hair colour
« Reply #1 on: 22/12/2003 00:57:30 »
When you present a certain trait (called a phenotype) your genotype (actual alleles present on the gene) can be either homozygous or heterozygous.  In other words, if your mom has brown hair, she either has two brown (dominant) alleles or one brown and one other recessive allele.  But it's often not that cut and dried...some genes can express themselves partially and traits can be affected by multiple genes.  

I don't know the exact genetics of hair color, but for simplicities sake, let me give you an example of how you could have red hair when both parents have brown.  Brown is the dominant gene and red is the recessive, right?  So, say both your parents are of the genotype Hh. (where H=brown hair and h=red hair)  They meet at a concert, get drunk, and *poof* you're conceived.  

Now, using a basic punnett square (which I am not recreating in ASCII here) you can see that there is a 1/4 chance of you having red hair.  Curly/straight hair works the same way.  The two probabilities crossed gives a 1/16 chance of you being a curly redhead.  

I'm not sure about eye color...there may be more than 2 alleles for it, but I'm pretty sure green and blue are BOTH recessive, but I'm not sure which takes dominance if both are present.  (probably blue)  One of the docs can probably answer this better than I can.  I take genetics next semester though!



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Offline tweener

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Re: Genetics of eye and hair colour
« Reply #2 on: 22/12/2003 02:04:35 »
I don't know much about genetics, but my father in law (dark hair) married a red haired woman and became a biology professor.  He used the calculations that cannibinoid is talking about above, and used himself and his wife as an example.  But he had to give up the example.  They had five children, all with red hair.  (Very pretty red hair I might add!)


----
John
 

Offline stevierar

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Re: Genetics of eye and hair colour
« Reply #3 on: 22/12/2003 12:01:41 »
Mehehehe, thankyou for your answers!
 

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Re: Genetics of eye and hair colour
« Reply #3 on: 22/12/2003 12:01:41 »

 

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