Polygenic (“many genes”) traits – controlled by more 2 or more genes. This is the case for most traits! – produce a wide range of phenotypes. Ex: Skin color Evidence indicates that skin color in humans is controlled by 3 genes – each of which have a dominant allele and a recessive allele. We represent the 3 genes as A, B and C, take a look at the example:

this example shows 2 individuals who are heterozygous for all 3 genes and have an intermediate skin color are crossed. A Punnett square for this cross would produce 64 possibilities for the offspring. What statements can be made about this graph?

The graph shows the probable outcomes of offspring. These individuals are most likely to have offspring with an intermediate skin color but can have offspring with very light skin or very dark skin. Most polygenic traits show a pattern like this – most individuals show a phenotype that is somewhere in the middle.

Gene interaction map CLAIM: epigenetic manipulation will be difficult… Evidence? Reason this evidence supports your claim?