an oversimplification of the world into “natural laws” that are poorly understood, usually surrounding a shallow understanding of survival of the fittest

It’s especially ironic because the only real measure of the “health” of any gene pool is its diversity. Species that lack diversity are doomed to go extinct sooner or later as the environment changes. The eugenics obsession with “racial purity” is the exact opposite of what you would want if you want your group to survive.