Expert: Walter Hintz - 10/8/2006

Question
Could you determine a person’s genotype if you knew his/her phenotype.  Why?

Answer
Hi Troy
 No because the phenotype is only telling us what genes are being expressed not what genes are present.  If you can construct a pedigree however with the phenotypes of the parents and/or children you can establish genotype.
 For example;  I have brown eyes and my wife does also. We have two children with brown and one with blue. That means that we must be heterozygous for brown eyes.  I also know my genotype because my father had blue eyes.