Eugenics is, according to Wikipedia, a social philosophy which advocates the improvement of human hereditary traits through various forms of intervention.
Granted, the article I read was ridiculously shallow and I'm too lazy to search for more detailed information, but doesn't every human being - or at least the ones in search of a mate - engage in some form of eugenics?
Women typically want tall men. We are attracted to each other through smell - pheromones present in our sweat let our mates' noses determine how genetically close we are. Men choose women depending on our sizes of our hips compared to our waists, because something in the 3-1-3 ratio signals fertility to them (incidentally, Coke bottles use this same proportion). We fantasize about what our children will look like. And how many we'll have. And why we'll have them, and why we want them to look that way.
And for those of us who, for whatever reason, can't have biological children, the option is there to choose the traits of the kids we do get, whether we obtain them through adoption, in vitro fertilization, and, I'm sure, a multitude of other approaches that I don't know about.
How is that not eugenics? Why is it a bad thing?