The tools in the genetic engineer's toolbox are not invented by humans, but discovered. We get them all from those master genetic engineers, our bacterial friends. The newest and shiniest of these is the so-called CRISPR-Cas system. Bacteria use it as a sort of immune system, but its potency comes from its ability to do rather selective gene editing.
Getting this system to work in a primate is a strong clue that it could also work for humans. In a decade or two it might well be possible for parents to have their offspring edited and revised for deleterious genes and maybe for looks, IQ, athletic ability and height to mention just a few.