I have some pretty strong feelings about eugenics (it's a good and necessary practice), but I find it very, VERY difficult to talk about it with anyone since I'm instantly labeled a Nazi for supporting it. I'm hoping the folks on Think Atheist will be more inclined to intellectual discussion than name-calling and dismissal.
The start off, some disclaimers: genocide is wrong; taking human rights away from people of a race/religion/hairstyle you don't like is wrong; concentration camps are wrong; violence in wrong.
There. Now to the actual discussion.
When I talk about eugenics, I'm talking about the practice of systematically removing debilitating genetic traits and defects from a population by means of regulating the reproduction of its citizens. Do you have Schizophrenia? Did you know that this ailment is genetic and very easy to pass on to you children? Please, do not punish an innocent child with this problem. Are you genetically healthy, intelligent, and talented? Do you have special immunities that make you less likely to get sick? By all means, spread these traits to future generations, either by having children yourself or donating to a sperm or egg bank. Do you want children but should not carry your genetic problems onto them? Adopt. Adoption will always be available no matter what the society (just because someone has good genetic material does NOT mean they would make a good parent). Do you say that adoption is not the same? Then I suppose you care more about satisfying your selfish desires than the well being of a child.
Eugenics is, at its base, very simple - think about the future first.
I'm leaving this post now for what I'm hoping will be thoughtful and anti-inflammatory discussion.
I would say that you are jumping the gun a bit. But the debate should not be dogmatic. You could use the exact same argument against legalizing homofilia in the 50ies mindset: sex certainly influence choice of sexual partners and the current argument is that it is abhorrent.
I don't think the subject is as easy to dismiss just because cosmetics may arise at a later stage. We've always allowed cosmetic alterations, everything from cosmetics to earrings to tummytucks, and it hasn't really become a massive problem of human depravity.
The possible Frankstein scenario is not realistic, nor is it a valid counter.