Offspring, edited

A few years ago, I signed up for 23andme. It’s a really simple, really well-designed genetic sequencing service: you spit in a tube, and three or four weeks later your genome is available online for analysis and perusal.

23andme does a lot of things right. They allow you to remain anonymous, and they provide a great deal of context for the results, curated by physicians. They discourage breathless hyperbole, opting instead for a reasoned, balanced explanation that cites various studies and makes it clear that much of your DNA is probability rather than certainty.

Back in 2008, when I wrote about the company for GigaOm, I had a conversation with its founder Anne Wojcicki about cavities. I don’t have any—which is unusual for someone of my age—and neither did she. A few weeks later, when I logged into the portal, there was a survey about tooth decay.

I don’t know whether our conversation triggered this discussion. But it underscores the power of a shared genetic platform. Unlike earlier genetic research, which sampled the DNA of a population, correlated it with a particular characteristic, and was finished, 23andme and its ilk are perpetually learning from their users.

As more and more people pool their genes, and then answer questions about their health, the data gets powerful fast. 23andme can take the outcome of these surveys and point researchers at genes that may have an impact on particular medical conditions—everything from wet earwax, to trouble sleeping, to whether you can see well at night.

Nobody’s genetic material is perfect. Consider four relatively innocuous facts about me:

• I’m sensitive to Warfarin, a blood thinner;

• I have a slower-than-normal ability to metabolize caffeine;

• I am at high risk of liver failure should I take an antibiotic called Floxacillin;

• and I’m more likely to develop psoriasis, a skin condition.

None of these is something I knew beforehand. All of them are things I’m happy I know now. At least one might save my life.

So it was that with the arrival of my daughter, we decided to sequence some more genes. Once she was around 3—old enough to spit in a tube with sufficient saliva to get a sample—my daughter joined the platform along with my wife and my mother.

Armed with several generations’ chromosomes, 23andme can do a lot more. You’re immediately struck by how real everything is: high school biology, with its study of blue-and-brown eyes and Mendel’s wrinkly peas, seems somehow theoretical; this is concrete. Those are my genes, next to my wife’s, and we can see exactly which genes went to my daughter.

And we know who’s to blame.

My daughter has the predisposition towards psoriasis, from me. Had the flip of the chromosomal coin gone the other way, she would have inherited that gene from my wife instead, and wouldn’t have it. The same is true for millions of other traits.

[A friend of mine, who is a genetic counsellor, shared a number of her thoughts on this post with me. She corrected me on the way I've phrased the preceding paragraph: "This phrase I found inaccurate. Because we all inherit one copy of each gene from our mothers and one from our fathers, Riley did inherit a gene from your wife. The correct way to look at this would have been had the flip of the chromosomal coin been different, she would have received the other copy of your gene that may not have predisposed to psoriasis (assuming that only one of the two of your genes carried this predisposition—if both of your genes had a variant that predisposes to psoriasis, there is no way she could have avoided this fate)."]

And this is where the inexorably slippery slope begins. Am I a bad person for giving my daughter psoriasis? If I could have done otherwise, would I?

How long until parents sit down and choose whose gene should go to the child? My teeth; my wife’s hair; and so on. That might seem far-fetched, but as Arthur Schopenhauer said, All truth passes through three stages. First it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.

Within a couple of decades, we’ll look at those who refuse to curate their children’s DNA the way we look at those who don’t vaccinate their kids—at best, scientifically ignorant; at worst, cruel and injurious to their offspring and society as a whole.

Once we’ve reached that point, what will happen when neither parent has a gene that works? If my wife were also afflicted with a propensity towards psoriasis, could we include a third-party gene that didn’t have the issue? It’d be like a sperm donor, but with far more surgical precision.

[Update: Coincidentally, a day after I wrote this, the UK approved three-donor in-vitro fertilization to allow parents whose genes contain hereditary diseases to have healthy children. Details here.]

But we all want a better world for our children. So it’s only a short leap from gene donors to genetic upgrades. How much would parents with a propensity for obesity pay for lean kids? How much would you pay for the right genes from a Nobel Laureate?

By that time, we'll be well into paid customization. Building our offspring will be like the modern version of rolling a character in a role-playing game. It’ll also be eugenics for the one percent, because the best genes, and the best sequencing, will cost the most money.

The burden on healthcare systems will be shocking; at the same time, parents will pay everything to help their children, even before conception.

Perhaps just as worrisome, we’ll be abandoning genetic diversity. We won’t just name our kids Brad and Angelina, we’ll breed them that way—without the chances of breast cancer, or whatever other genetic baggage we need to shed. The breadth of human genes will narrow considerably, particularly among well-to-do populations.

The problem with genetics is that it deals in probabilities. There isn’t a clean one-to-one relationship between a particular gene and a physical attribute. If we optimize a gene for one thing—say, higher IQ or better leg muscles—we may be stifling something else along the way.

Consider, for example, the genetic mutation that causes sickle-cell anemia—and can offer immunity to malaria. Or the one behind Tay-Sachs that increases resistance to Tuberculosis. Both mutations occur in populations where the diseases are more common, and would therefore convey a genetic advantage.

If we're not careful with our editing, we might need the genes we’ve discarded for reasons we don’t yet know. Put another way, if there’s no genius without madness, no flight of creative mania without drag of deep depression, then we have to take a much longer view of how we edit our offspring—lest we cull delight when weeding out misery

We’ll have gone from a messy, varied, highly adaptive gene pool to a homogeneous bathtub. In Against The Fall Of Night, Arthur C. Clarke postulates a future in which human bodies have been optimized beyond usefulness. There’s no hair, and no fingernails, because these are superfluous. But there’s also no risk-taking, and no adventure, and no agitation. It’s a bleak end to the species.

But what's abundantly clear from seeing how far 23andme has come is that it's only a matter of time before not curating your child's DNA is considered inhumane, irresponsible, and maybe even illegal.