Here’s the brilliant SLATE science editor William Saletan on rapid slippery-slope developments in preimplantation genetic diagnosis, the procedure used to weed out defective embryos. It’s easy to imagine a time not too far down the road when having the babies the old-fashioned or unimplanted way will be viewed as involving too many risk factors to be acceptable. And so sex, in the name of safety, will be completely separated from reproduction.