As described in a patent recently granted by the United States Patent Office, consumer genomics company 23andMe has developed a system for helping prospective parents choose the traits of their offspring, from disease risk to hair color. Put another way, it's a designer baby-making system.

The company says it does not intend to use the technology this way. "When we originally introduced the tool and filed the patent there was some thinking the feature could have applications for fertility clinics," said Catherine Afarian, a 23andMe spokeswoman. "But we've never pursued the idea, and have no plans to do so."

Filed in December 2008, the patent — number 8543339, "Gamete donor selection based on genetic calculations" — sounds like something out of Gattaca, the 1997 movie that came to symbolize tensions between self-determination and biologically ordained fate.

The patent describes a technology that would take a customer's preferences for a child's traits, compute the likely genomic outcomes of combinations between a customer's sperm or egg and other people's sex cells, and describe which potential reproductive matches would most likely produce the desired baby.

Among the traits listed in the application as examples of possible choice are: height, weight, hair color, risks of colorectal cancer and congenital heart defects, expected life span, expected lifetime health care costs, and athleticism. The company, which has about 400,000 customers, offers genomic analysis of more than 240 traits altogether, from Alzheimer's disease risk to breast shape and memory. Additional traits from this longer list could presumably be used the same way.

A figure illustrating how 23andMe's patented trait-selection system could hypothetically work. Image: U.S. Patent and Trademark Office

In some ways, this type of selection is theoretically available to people now using pre-implantation genetic diagnosis, or PGD, an assisted reproduction technique in which doctors scan an embryo's genome before it's implanted in a woman. However, PGD is currently used to prevent serious genetic diseases or, in a small but growing number of instances, to pick a baby's sex.

Clinics offering PGD don't give customers a list of possible, non-medically relevant traits to choose from. That's actually illegal in Canada, the United Kingdom and Australia. A short-lived plan by U.S. fertility specialist Jeffrey Steinberg to offer hair- and eye-color selection ended in 2009 in a storm of public condemnation.

Some women who conceive using in-vitro fertilization and donated sperm, which accounts for roughly 50,000 pregnancies each year in the United States, do practice a form of selection, but in very broad terms. They typically look at general information, such as the traits, life history and health background of sperm providers, rather than genetic profiles.

As detailed in 23andMe's patent application, this type of information often misses important medical details, such as genetic risks not evident in family histories. The company's patented system would included that information, and also offer more fine-grained control over a baby's traits. Its potential market could include not only women using assisted reproduction, but also people who've had their genomes sequenced and are curious how their progeny might turn out. If that happened, baby-designing might establish a market foothold.

"It would be so irresponsible of 23andMe to actually offer a product or service based on this patent," said Marcy Darnovsky, executive director of the Center for Genetics and Society, a bioethics think tank concerned with the responsible use of genetic and reproductive technology.

Not everyone would agree: though polls suggest that most Americans oppose screening for non-medical traits, some people argue that "designing" babies by selecting traits like intelligence is no more sinister than sending them to good schools or doctors, and that selecting traits like eye color isn't especially harmful .

Regardless of one's position on trait selection, 23andMe's Afarian says that it's not a concern. The patent covers 23andMe's Inheritance Calculator — an existing service that predicts the likely eye color, alcohol metabolism, earwax composition, bitter-taste perception, lactose tolerance and fast-twitch muscle composition of customers' offspring — but the Calculator won't be expanded to include other traits, Afarian said.

"There are no immediate plans to update the Inheritance Calculator, or do anything other than what we're doing now," said Afarian. If customer demand existed for other services or features in the future, 23andMe would respond, but the demand for trait selection simply isn't there right now, she said.

Geneticist Daniel MacArthur of Massachusetts General Hospital said he's not especially concerned about moral objections to selecting offspring traits with the type of technology described in the patent, but he thinks it's important to be realistic about what's even possible.

When 23andMe filed its patent in 2008, the results of large-scale population genomics studies were just becoming apparent. Many researchers expected that the genetic underpinnings of complex traits and diseases would soon become apparent; in general, they've been disappointed.

Advances have been made in understanding traits and conditions driven by activity in one or a few genes, but those are biological exceptions. Most of what people want most to understand, to give or avoid giving to their children — intelligence, character, freedom from chronic disease — is extraordinarily complicated.

Of what can be attributed to nature rather than nurture, only a small-to-medium-sized fraction can presently be linked to what's found in a genome scan. Even for traits like height, which are relatively straightforward and well-studied, scientists can now account less than half the role played by genetics. For some traits, such as athleticism and the overstated importance of fast-twitch muscle, there's a discrepancy between what's being measured and what actually matters.

"We're not there yet," said geneticist Nathan Pearson of Ingenuity Systems, a genome analysis company, of linking genotypes to complex traits. A good rule of thumb, said bioethicist Tom Murray of the Hastings Center, who helped set up the ethical arm of the Human Genome Project, is that the power of genomic prediction declines in inverse proportion to the importance of what's predicted. The likelihood of bitter-taste perception might be easy to estimate, but not longevity.

To Darnovsky, designer babies are in a sense less troubling than our ideas about them. Overestimating the importance of genes could lead people to underestimate the importance of everything else, as when Elysium director Neill Blomkamp argued that social equality can only be achieved through genetic engineering.

"The stories that we tell about what's affected by genes, what does and doesn't matter, is what's at stake," Darnovsky said. "If we come to believe that we can select certain traits in our children, and that's the best we can do for the human condition, then we're in bad shape."