system
Given the following post, respond as if you're commenting on Reddit:
human
There Isn't a Good Argument Against Genetic Screening and Eugenics, CMV

This is assuming that we don't creen based on race, and assuming that those that are handicapped aren't screened out if they have something to contribute to humanities future (Tesla, Turing, Hawking are all people who would have been "screened" out in an earlier world)
gpt
>Assuming we don't screen based on race

Every major eugenics project has believed it was working 'ethically'. We now believe all of them to have been horrifically wrong and a thinly-veiled exercise in ideology.

> if they have something to contribute to humanities future

How on earth will you know if that particular smear of DNA you're examining under your microscope is going to contribute to humanity's future? 

It is nearly impossible to imagine a system that could be set up which wouldn't be subject to corruption, nepotism and cronyism. And those are only the top-down problems. The public in general can be terribly biased, prejudiced and misinformed. How will it resist the public pressure to turn the system against 'the mexicans' or 'the gays' or some other hate-group of the week?

And those are only the ethical problems. The practicalities of running a national screening/eugenics programme are immense. All those tests, who pays for them? (The applicants themselves? That'll stop 'the poor' from trying to have kids, eh?) How do you stop people from reproducing as they've always done? Obligatory birth control? Compulsory reversible sterilisation? On kids of thirteen? How will you enforce all this? 

Lastly, while we understand much more of genetics than they did in the thirties, the last time eugenics was tried on a large scale, that understanding has shown us that genetics is *complicated*. Some diseases have simple single-gene causes. Others involve dozens or hundreds of genes interacting in ways we do not yet understand. Any national eugenics programme would be, scientifically speaking, fumbling in the dark.