What is immoral about eugenics?

It is a "given" in discussions of genetic engineering that no sensible pers on tan be in favour of eugenics. The main reason for this presumption is th at so much horror, misery, and mayhem have been tarried out in the name of eugenics in the 20th century that no person with any metal sense could thin k otherwise.(1-3) In fact, the abysmal history of murder and sterilisation undertaken in the name of rare hygiene and the "improvement" of the human s pecies again and again in this century is so overpowering that the risk of reoccurrence, sliding down what has proved time and time again to be an ext remely slick, slippery slope, does seem enough to bring all ethical argumen t in favour of eugenics to an end.