MadSci Network: Genetics

Re: Why do some blonds turn into brunettes when they have recessive genotypes?

Date: Mon Feb 5 23:19:20 2001
Posted By: Greta Hardin, Secondary School Teacher, Science
Area of science: Genetics
ID: 980964549.Ge

Changing hair color....

It turns out that hair color is more complex than just a single gene.  
Actually it is a set of genes... and the ones that are active depend on your 
age.  In the same way that you produce growth horomones through a certain 
age, and then quit - thank goodness - the genes in charge of hair color 
shift.  It turns out you may have a series of genes in charge of hair color.  
At one point your "young" genes are in charge - and you may be a light 
blonde, or a bright red-head.  Over time, the horomone balance in your body 
changes, and your "adult" genes take over.  As a result, your may become a 
dark blonde, or your red hair may turn auburn.  In a few populations blonde 
is blonde is blonde... these tend to be those of the most northern Nordic 
descent.  For what ever reason it was good for survival reasons to remain 
light blonde... and that trait has remained.  But for most populations, for 
a variety of reasons, hair darkens as you age.

Hope this helps... 


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