Just for the record, I disagree with you based on my study of human development and embryology. Post #32 was sarcasm. I am unsure if your post is sarcasm as well.
I do not believe that just because someone may die of cancer someday is a good reason to prevent them from reaching that stage.
I think this practice of screening embryos is just to ease the minds of parents who just couldn't stand the thought that "their perfect baby" could have a genetic "defect".
People need to grow up. Maybe their "perfect" baby will become an alcoholic.