In the genetic mapping exercise we have talked about this semester, mutant virgin female flies were mated with wild type male flies and the phenotype of the F1 offspring from this first cross were scored and used to set up a second cross on March 1. When the first F2 progeny begin to emerge, they seem to be mostly wild type flies. Explain why we might see this and how these results might affect the genetic map we are creating from the F2 data.