Question about eye color

Megan Igo megan at ucla.edu
Fri Mar 15 17:06:56 EST 1996


In response to this set of messages, it is also important to keep in mind
the fact that like most phenotypes, there is more than one set of alleles
that control eye color, and the combination of genes that one gets from two
blue eyed parents could, potentially, produce a brown eyed child, but the
likelyhood of this, as was stated by Bill Tovel, is quite low. Brown eye
color is typically dominant to blue in humans, but the number of different
eye colors seen in human populations (and in single families) is due to
combinations of genes, not just one gene.

                cheers,
                        Megan
                        megan at ucla.edu
>Michael Rivero (rivero at accessone.com) wrote:
>
>:   What is the likelyhood that two blued parents will produce a brown
>: eyed child?
>
>Dear Michael,
>        Unless they work in show business with very young actors, the
>likelyhood is very small.  The eye color allele for brown eyes is dom-
>inant, which means that in order to have blue eyes, one must have two
>copies of the allele for blue.  Thus, two such parents would have no
>copies of the allele for brown between them, and they would not produce
>a brown-eyed child.  However (there's always a catch) there are possible
>exceptions where the eye color allele is for brown, but some other gene,
>e.g., in the melanin production system, is faulty.  In this case, one
>parent could provide the brown allele, and the other could provide a
>working copy of the faulty gene, and their child could have brown eyes.
>Since each parent could, in theory, have different faulty genes which
>impact eye color, but still have the brown allele, it is possible that
>such parents would produce *only* brown-eyed children.  The frequencies
>of the faulty genes are low, so the likelyhood is low, but not zero.
>                                Yours,
>                                Bill Tivol





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