Eye Color Question

Rcjohnsen rcjohnsen at aol.com
Mon Mar 8 20:37:21 EST 1999


<< If both parents have blue eyes, MUST their children also have blue
eyes? (Explanation also appreciated!)
    THank you!!
       Frank >>

NO!  It is common for teachers talking about general inheritance patterns inn
eye color to tell students that eye color is a single Mendelian factor-that
brown wyw color is dominant to blue eye color.  Hence most people believe that
brown yed parents*BB X BB) will have all brown eyed children, that Bb X Bb will
have 3 brown to one blue and that bb X bb blue X blue must have all blue eyed
children.  Eye color is not monogenic but  inherited polygenetically ie. there
are several different genes that contribute to eye color.  The blue one sees 
depends upon very small granules in the iris which are coated with pigment(in
the case of blue--not very much).  Light is refoected back to the observer in
the blue spectrum.  As eyecolor becomes darker the granules become more
numerous, larger and coated with more pigment.  I have seen eyes that were
violet, blue, greenish, yellowish, light hazel, brown,  black, as I'm sure you
have.  I have know blue eyed couples with brown eyed children and as a brown
eyed man I can assure you I had nothing to do with it.

Enjoy,
Roger




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