It is easy to modify our phenotype just by having a plastic surgery, and it doesn't affect the genetics of all of our offspring. Changing genome, on the other hand, is a much more consequential in that regard. On the other hand, it is also a fact that each of us is an owner of their body, and can practically privately try to do to their bodies whatever they please.
The differentiation of species could potentially lead to the diversity of humans on a par and greater than the diversity of dogs. This category is both for the "how" and the "why" of low-to-high level self-modification.