Until just a few years ago, making a baby boy or a baby girl was pretty much a hit-or-miss 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, Va. And baby Jessica is just the beginning. Within a decade or two, it may be possible to screen kids almost before conception 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, what sorts of illnesses they will be naturally resistant to, 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 is many years old, 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 used to cosmetic surgery and psychopharmacology, this is not a big step.” The prospect of designer babies, like many of the ethical conundrums posed by the genetic revolution, is confronting the world so rapidly that doctors, ethicists, religious leaders and politicians are just starting to grapple 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 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 the idea of engineering genes in or out of a fetus. Besides, say clinicians, even if the techniques for making designer babies are perfected within the next decade, they should be applied in the service of disease prevention, not improving on nature. But what doctors intend is not necessarily what’s going to happen. Indeed, the technology that permitted the Collinses family to pick the sex of their child was first used to select for health, not gender per se. Adapting a technique used on livestock, researchers at the Genetics & IVF Institute in Fairfax took advantage of a simple rule of biology: girls have two X chromosomes, while boys have one X and one Y. The mother has only Xs to offer, so the balance of power lies with the father–specifically with his sperm, which brings either an X or a Y to the fertilization party. As it happens, Y chromosomes have slightly less DNA than Xs. So by staining the sperm’s DNA with a nontoxic light-sensitive dye, the Virginia scientists were able to sort sperm by gender–with a high rate of success–before using them in artificial insemination. The first couple to use the technique was looking to escape a deadly disease known as X-linked hydrocephalus, or water on the brain, which almost always affects boys.
