That's not true at all, genetics only play a part in the mental development of a person, much of it is instead related to the environment where a person has been growing.
It is as with talent, some people are better than other at certain activities but even the most gifted person cannot compete with a professional who has spent his life training and studying his craft.
The same can be said for "intelligence": if you are never taught to think you'll never think once in your lifetime, even if you are the exact copy of Leonardo da Vinci; on the other hand, even if you are thick as a rock but you've been growing in a society focused on your development you'll be able to become a normal person.
Eugenetic politics do nothing for humanity betterment, social structure is much more important IMHO
It's useless to cite Karl Popper to centrists, they are just rightoids who don't have the courage to admit this simple fact to themselves first and to the world at large second.
Just like most Nazi are closeted homosexuals who cannot understand their natural urges and act against them for some bullshit reason