Eugenics is the pseudoscience of trying to create a master race of humans by selective breeding.
Actually it's not pseudoscience, it's very real science, however the notion that it can create a master race is questionable, but selective breeding isn't questionable at all because humans selectively breed all the time. It's just that normally it would be the two humans in question making the choices rather than an outside entity.
But even then, outside people have been making those choices for millennia. That's what arranged marriages are all about. The matchmaker or the two families agree on who will marry.
That IS selective breeding in every respect.
And then we get to the very definition of "master race" itself.
Is a master race put together with the intention of its members being smarter, healthier and more desirable, or is it an effort to confine the genetics, or is global domination the objective?
The first one is just human nature. People naturally want to breed with smarter, healthier and more desirable partners.
Water however, seeks its own level, doesn't it?
The other two are both foolish and dangerous because they've both been tried countless times. The latter racial restriction, is downright dangerous because Nature doesn't tolerate racial purity.
Eventually such restrictions begin to turn out a race of retarded people. See Fundamentalist Latter Day Saints, where insular communities in Arizona, Colorado and Utah are experiencing profound mental disabilities in an alarming number of births.