How would genetic engineering cheapen humanity?
We already use a number of technologies (and natural methods) to try to make our bodies more "perfect". What is it about genetic engineering that makes it different than these other, largely acceptable methods?
For one thing, scientists know so little about genetics to begin with, that it's treading on very dangerous ground messing with genes, the very components that make a human being who and what they are. There will be unintended consequences.
Another issue is that it reduces the child to a commodity to be bought or sold based on desirability. It cheapens life. *Oh, you're not prefect. We don't want you.* Then what do you do with this imperfect child? Destroy the embryos because they didn't meet our qualifications for a *perfect* child? Killing children like squashing fruit flies is not the answer.
I know a man who was born handicapped and his parents were told to institutionalize him because he would never amount to anything. The man is a genius even with physical handicaps. And look at Stephen Hawking. Another example of someone who would have not been *chosen* because of his genetics.
And when you mess with genes, who says it only affects the physical?