Until just a few years ago, making a baby boy or a baby girl was pretty much a hit-or-miss (偶然的，碰运气的) affair. Not anymore. Parents who have access to the latest genetic testing techniques can now predetermine their baby's sex with great accuracy, as Monique and Scott Collins learned to their delight two years ago, when their long-wished-for daughter Jessica was born after genetic prescreening at a fertility clinic in Fairfax, Virginia. And baby Jessica is just the beginning. Within a decade or two, it may be possible to screen kids almost before pregnancy for an enormous range of attributes, such as how tall they're likely to be, what body type they will have, their hair and eye color, and even, conceivably, their IQ and personality type. In fact, if gene therapy lives up to its promise, parents may someday be able to go beyond weeding out undesirable traits and start actually inserting the genes they want, perhaps even genes that have been crafted in a lab. Before the new millennium, parents may be going to fertility clinics and picking from a list of options the way car buyers order air conditioning and chrome-alloy wheels. 'It's the ultimate shopping experience: designing your baby,' says biotechnology critic Jeremy Rifkin, who is appalled by the prospect. 'In a society which is using to cosmetic surgery, this is not a big step.' The prospect of designer babies, like many of the ethical problems posed by the genetic revolution, is confronting the world so rapidly that doctors, ethicists, religious leaders and politicians are just starting to grapple (格斗) with the implications, and trying to decide how they feel about it all. They still have a bit of time. Aside from gender, the only traits that can now be identified at the earliest stages of development are about a dozen of the most serious genetic diseases. Gene therapy in embryos (胚胎) is at least a few years away. And the gene or combination of genes responsible for most of our physical and mental attributes hasn't even been identified yet, making moot (无实际意义的) the idea of engineering genes in or out of a fetus (胎儿). What is gene therapy supposed to do to live up to its promise?