The plain truth is that there is a good and bad side to everything. This applies to genetics to. Non-Mendelian inheritance makes things much more complicated, as it is basically a collection of exceptions to the rules of Mendelian genetics. What's the good side? Well the good side is that without Non-Mendelian genetics there would be no evolution or variation. You see in Mendelian genetics the alleled cannot change and form new types. Therefore what you start with is also what you end with. However, in Non-Mendelian genetics Mutation and Incomplete dominance both add new phenotypes, while Mutation adds new genotypes also. This makes Non-Mendelian genetics extremely important.