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Will genetic choice make sex obsolete?

Anyone hoping to shop for blemish-free, farm-to-crib babies with no diseases and a poet’s soul will be disappointed

Dan Samorodnitsky

Senior Editor

Reading scientific literature, you might think that biologists approach problems as an opportunity to keep their DNA sequencing machines warm. That's an approach that creates real, actual problems. I’ve read the phrase GWAS (genome-wide association study) so many times I can’t stop hearing it as a blaring noise in my head.

A GWAS is a technique that can suss out the genetic source of a particular characteristic by looking at entire genomes. If you were a scientist really interested in, say, hemophilia, you might do a GWAS using the bones of the Habsburgs and discover the genetic mutation that causes the disease. And that’s great. Let no one say I don’t endorse gene sequencing for investigating all kinds of things. Disease-causing mutations, finding genes involved in blood clotting, one family’s history of incest, whatever.

If you knew hemophilia ran in your family, and a doctor told you that preventing your children from inheriting it was possible, most people would probably do it. “By the way,” the doctor might say, “while I’m reading this infinitely long scroll with your genome printed on it, it looks like your children could be at increased risk for a few other things too. Do you want to sort that out while we're at it?”

'Easy PGD'

That’s (kind of) the world that’s coming, according to Henry Greely, a lawyer and bioethicist at Stanford. His book, The End of Sex and the Future of Human Reproduction (the first four words are much larger than the final six on the cover), was published in 2016; the paperback comes out this Spring. In it, Greely discusses the idea that pre-implantation genetic diagnosis (PGD), the process of testing embryos for some genetic diseases before they can be implanted and develop, can be furthered into what he calls “Easy PGD.”

Easy PGD is a two-step process: the first converts skin cells into stem cells, which are then themselves converted into sperm or egg cells that can be used to create an embryo. Second, souped-up gene sequencing technology will make selection of an embryo with the parents’ choice of genetic features … easy, and take sex out of the process.

Sounds great! Being able to make gametes from skin cells opens up an entire world of possibilities. People suffering from infertility, or same-sex couples, or couples carrying mitochondrial diseases, could have children that were genetically their own. It also opens up things that are less “possibilities” and more “unsettling questions.” For instance, Greely asks the reader if “uniparenting,” where sperm and egg are generated from one person, is OK. Is it incest?

Harvard University Press

The greatest strength of The End of Sex is Greely’s willingness to go there, to think through the unsettling possibilities from every angle. Genetically, uniparenting is unquestionably incest – if anything, more incestuous than was previously possible. But, if the embryos that result can have their genomes sequenced, and any diseases that arise from this bizarre, self-involved coupling can be filtered out, what’s the harm?

Going there

That is the biggest question. What is the limit of the filter? How much can gene sequencing say about our futures? Anyone hoping to shop from a grocery store selection of blemish-free, farm-to-crib babies with no diseases, a seven-foot wingspan, and a poet’s soul will be disappointed. Greely writes much the same in The End of Sex. That Easy PGD will become a part of life, in some way, is hard to argue with, since, as Greely points out over and over again, most of the working parts already exist – stem cell research is one of the most active fields, regular PGD has existed for decades, and gene sequencing gets cheaper (though not necessarily better) every year.

In other places, Greely has argued that hand-wringing about modifying humans is already at a sufficient level, though he isn’t judgmental in the book about peoples’ concern. And he's right: pearl-clutching about technology's affect on human reproduction, and concerns about how that tech will turns us all into machines or something, goes back decades, and so far as I can tell everyone is still human. He is very optimistic about how it will become widespread, stating that since it will benefit mankind in both health and economy, it will wise for insurance companies to pay for it and for the government to refrain from interfering.

I don’t know. It’s hard for me to look at the political landscape and think that in 20 to 40 years, as Greely predicts it will take for Easy PGD to take hold, any kind of large-scale consensus like that will coalesce. Roe v. Wade was more than 40 years ago, and reproductive rights are still constantly under attack. For decades, commentators have been calling for increased access and loosened regulations on reproductive education and access precisely because it would benefit the economy. 

That argument hasn't had much success in the United States, though it has in other places (for instance, Spain performs a disproportionate amount of Europe's PGD, in part due to ahead-of-its-time legislation and a friendly economic environment). North Dakota and Indiana have laws banning abortion after a Down syndrome diagnosis, and although Indiana’s has been blocked by a federal judge, Ohio just passed one of their own. But Greely himself pointed out to me that abortion and PGD are not the same thing, and the latter hasn’t been targeted in the same way as the former.

I don’t want to be the skeptic naysayer who doubts the future will be any different than the present. That person, time and time again, eats dirt. And there’s a prevailing attitude among scientists and science-observers that computational analysis and gene sequencing are a panacea. But, knowing what gene – and what mutations or variations or modifications – cause a disease or contribute to a characteristic can take decades of work, if it can even be done at all. No matter the number of sequences you gather – a genome, proteome, biome – they won’t necessarily add up to a blueprint that can be read like the plans for a building.

Not that you asked (though you kind of did by reading this far), but I think Easy PGD will exist, just maybe not in 20 to 40 years, and not commonly used. It’s hard to get between people. Judge for yourself; Greely writes with the verve of a lawyer and zest of an academic, but The End of Sex will open your mind to a future you might not have anticipated.