# Why do we apply the mutation operation after generating the offspring?

Why do we apply the mutation operation after generating the offspring, in genetic algorithms?

For example, suppose that you have 4 possible genes $$A$$, $$B$$, $$C$$, and $$D$$, and that your chromosomes have a non-binary encoding. In that case, if no member of your population has the gene $$D$$, then no amount of crossover operations will result in the introduction of that gene.