Anyone Else Feel Guilty About Changing a Sim's Genetics?

I'm a controlling simmer. I will generally leave most sims alone but the ones that are too ugly for my tastes or don't fit the look I want for them, I will change. Especially townies and premades like Nina who, for some weird reason, looks nothing like her mother or sister. I can't stand it so I always change her. Some of the premades are weirdly skinny so I'll edit them to have more realistic proportions (like Candy).