Rather than have any of them implanted, she opted to use donor sperm and bear a child with normal feet but no biological tie to her husband.
“There's no doubt that this area is a slippery slope,” Dr. Tan says. “But at the end of the day, this technology evolves in pace with society's values.”
The New York University School of Medicine surveyed 999 people in 2009 and found that most supported prenatal screening to eliminate serious diseases, along with mental retardation (75 per cent) and blindness (56 per cent). At least 10 per cent also favoured improving height and 13 per cent considered superior intelligence acceptable.
But Julian Savulescu, the controversial Oxford University bioethicist, believes that society must do more than be tolerant. He claims parents have a moral obligation to select embryos that are “most likely to have the best life, based on the available genetic information.”
That information, he argues, should not be limited to avoiding disease genes, but should include those that might improve intelligence or physical characteristics – even if it maintains or adds to social inequalities. He calls it “procreative beneficence.”
Prof. Savulescu, whom Dr. Nisker has often debated, also believes that society should embrace the genetic manipulation of embryos to endow future offspring with superior traits that inheritance has not provided. Until recently, such engineering was only theoretical. But in 2007, researchers at Cornell University quietly created the world's first genetically modified human embryo by adding a fluorescent gene that allowed scientists to watch it develop. The breakthrough did not become public until the following year, when it was roundly condemned as a worrisome step toward designer babies.
Despite the evolutionary aspirations of people like Prof. Savulescu, Ms. Darnovsky of the Center for Genetics and Society suspects that PGD is too expensive and invasive to be adopted widely. But even with limited use, she says, “the danger is we would be reinforcing the inequalities we already have to a shameful degree and introduce new inequalities where only some people have these traits.”
She also worries that parents who go to great lengths to stack the genetic deck of their children will place undue expectations on them. “In a way, it's a closing off of the child's future,” she says, since the parents have tried to predetermine what their strengths should be.
What's more, parents who turn to PGD as a means to avoid a specific condition may also decide to test for other traits while they are at it. “I think that what happens,” Ms. Darnovsky says, “is that we start to look at our children as we look at remodelling,” as when painting the front porch somehow leads to a full home renovation.
Dr. Steinberg agrees. “People might say one thing publicly about what they'd want in their children, but when you sit down and talk about we're going to do, they start asking about other things: intelligence and height.”
Regardless of what people want, Dr. Handyside insists that the concept of the “designer baby … has no merit.” PGD is limited by the genes the parents already have, he says. As well, the number of embryos parents have to choose from is limited by the fact that often only a few can be created by IVF at a time – making it extremely unlikely that any one could cherry-pick a desired combination of traits to produce, say, a blond, muscular Mozart.
“There are over eight million possible genetic combinations,” he says. Even still, the selected embryo could be miscarried or develop a mutation in the womb. At best, he says, “the genetic snapshot will provide a fuzzy photo of each of your prospective children.”
Jonathan Kimmelman, a genetics researcher and bioethicist at McGill, notes that, while science has made it feasible to select against certain genes, selecting for them to predict traits is much trickier. “Genes are not determinants,” he says, adding that a great many of them have a very small impact on the same characteristics and “interact with environmental cues about which we know very little.”
Yet, to some who offer embryo screening, the limited power of genes bolsters the argument that it is harmless to select them.