Sorry thought you were older and would understand the history.
There was a regime in the 30’s, 1930’s that is, that believed that they should purify the racial mixture of their nation so that they would have a homogeneous population. The lack of diversity, everyone having a consistent and similar “starting point” as you advocate apparently couple being bred to the highest standards (you certainly did not imply this) would result in not only a highly content population but would transform into a dominating power on the back of their master race.
America is the land of opportunity which leads to better outcomes as a nation. Nobody is guaranteed an outcome. Our diversity, people coming together from all walks of life- rich, poor, advantaged, disadvantaged, etc and from a wide range of ethnic backgrounds weaves us a fabric superior to all other nations. Many seem to have forgotten that.
It’s why when you look at the demographics of the rich, it’s rare that you have a family spanning more than 4 generations maintain its wealth and status. They are replaced by newly rich and the old money loses their stature. 70% of families lose their wealth by the second generation, 90% by the third.
You can population engineer all you want and affix whatever label to that you want, but the basic premise is very unsavory. Provide opportunities and let people flourish for themselves or not depending on whether they really want to. Try to give it to them and it will never happen.