Hsu offers another chilling scenario: What if the Singapore government, as an example, were to invite his company to alert parents if one of their embryos is likely to be well above average intelligence? Hsu can imagine a situation where “I guess in Singapore it is okay but we don’t feel like Americans are ready for it.”34 If and when Americans decide they are ready for it, I expect Hsu would be happy to oblige. Editing embryos for intelligence remains a fantasy, but ranking embryos via PRS doesn’t look so far away.35
Hsu’s critics argue that selecting embryos based on PRS is risky business, rife with statistical ambiguity, geographic bias, and ethical fragility. “It might be better than a horoscope, but we don’t know—but I don’t think that Genomic Prediction does either,” observes Hank Greely.36 An Israeli study concluded that the gain afforded by PRS calculations—the difference between the “top ranked” embryo from the average—was about 2.5 cm for height and 2.5 IQ points.37 That’s hardly enough to justify the expense and hassle of IVF. “The prediction is not good enough to individually identify an embryo with a certain characteristic,” Kathiresan told me. “There’s not a 1:1 correlation between score and outcome. It’s a probabilistic model. It’s not appropriate in my view to use for embryo selection.”38
Even if you disagree, geneticist Laura Hercher warns that Hsu’s company can’t guarantee giving a couple a child that is not going to get sick and die. “If you are buying into that fantasy, you’re going to be angry. I hope that it is at [Genomic Prediction] and not at your kid,” she says.39
Assuming that CRISPR or base or prime editing is safe (or no worse than the mutation rate caused by background radiation) is there any fundamental reason why it should not be allowed on human embryos for whatever applications we deem to be appropriate? In 1997, at the halfway point of the Human Genome Project, UNESCO declared the human genome to be a priceless heirloom. “The human genome underlies the fundamental unity of all members of the human family, as well as the recognition of their inherent dignity and diversity. In a symbolic sense, it is the heritage of humanity.”40
It’s a splendid line, but is the human genome really the heritage of humanity? The sacrosanct property of humankind, to be preserved and protected like a priceless masterpiece? Look but please don’t touch? “It seems the equivalent of The Ark of the Covenant,” Greely declared. And, as anyone who saw the Indiana Jones film Raiders of the Lost Ark knows, “it cannot be allowed to fall into the wrong hands.”41 The human genome belongs to all of us, argues Françoise Baylis, but there is no pristine genome exhibit we can put on display as the perfect sequence of the genome. What we have instead are 7.5 billion genomes, all iterations of what went before and their future descendants.
What, then, was the Human Genome Project if not the definitive textbook sequence? The fabled reference genome that President Clinton announced in June 2000 was a patchwork quilt with a dozen anonymous contributors. A decade later, major advances in DNA sequencing technologies made it feasible to have your own genome decoded. In 2010, I attended a conference at MIT where the first two dozen genome pioneers gathered under one roof, including Jim Watson, Harvard’s Henry “Skip” Gates, and George Church.42 A few notables, including Craig Venter and Black Sabbath’s Ozzy Osbourne, were absent, but I sensed that this would be the last time that (almost) every person sequenced on the planet was in one room. But nobody was proposing to anoint any individual genome to represent the human species. The genome of a Beckham or Beyoncé is littered with mutations just like yours and mine.
While there is nothing sacrosanct about the human genome, there is widespread opposition to the notion of tampering with the germline, knitting by hand a permanent sequence alteration that would be passed on to future generations. But in a practical sense, editing a human embryo is a much safer proposition than treating a child or adult. Church argues that germline editing offers three intrinsic advantages. First, it is more effective than other delivery systems at reaching all cells in the body. Second, after administering the edit, every future child and descendant would receive the edit free rather than costing millions of dollars for their own somatic gene therapy. And third, germline editing goes through a single cell, whereas somatic therapies impact millions of cells—assuming we can sort out delivering genes to the brain or other hard-to-reach organs—any one of which could become cancerous.43 “Somatic gene therapy has been hopeless as a therapy, because you’ve got to get the gene to billions of cells,” says Savulescu.44
There is no inviolate reason why we should not contemplate germline editing, and indeed there are arguments in favor from a medical and economic standpoint. But that still doesn’t answer the question of why or when? “Proceed with caution” is a common refrain whenever a new genetics technology looks poised to transform medicine and assisted reproduction. It was the title of Neil Holtzman’s book in the 1980s warning of the potential dangers of prenatal DNA diagnosis. The Lancet editor Richard Horton echoed the phrase shortly before the birth of the CRISPR babies.45
That’s reasonable, but what if deliberately refusing to alter the human genome affects the future just as if we allow germline intervention? “If it ever became possible to eliminate, say, the gene that causes cystic fibrosis, not then to do so would condemn future generations unnecessarily to suffer from a wretched condition,” writes Kenan Malik. “There is nothing ethically superior in leaving things be if it is possible to change them for the better.”46
What if we wanted to correct a devastating gene mutation? Huntington’s disease (HD) only affects 1 in 50,000 people, but it is incurable. Children of HD patients have a 50:50 chance of inheriting the disease gene. In the Ken Burns documentary The Gene, Jenny Allen makes the fraught decision to take a genetic test that will reveal her destiny. Her mother and two of her siblings have HD. As her doctor reveals that she did not inherit the defective gene, Jenny bursts into tears, waves of joy and relief mingled with survivor’s guilt. One day, germline editing could permanently fix this mutation, snipping out the faulty sequence to restore a functioning version of the HD gene. “Why should anyone object if the genome of the 50,000th person is coaxed back to the normal conventional sequence?” Greely asks reasonably.47
Savulescu goes further, arguing that parents have a downright obligation to maximize the potential of their children. Eradicating genetic disease is not bad in itself, he says, but our technology won’t stop with reverting to healthy forms of genes. We could introduce novel variations that have not been encountered in our species before.
In the summer of 2015, after the initial furor around CRISPR and human embryos, Harvard professor Steven Pinker wrote a strident op-ed in the Boston Globe. In a world that promised a biomedical bonanza to improve people’s health and longevity, Pinker argued, “the primary moral goal for today’s bioethics can be summarized in a single sentence. Get out of the way.”48 While individuals must be protected from harm, a “truly ethical bioethics” should not hold back research in red tape or moratoria, nor should it sow panic about potential future harms or bandy about perverse analogies with Nazi atrocities or science-fiction dystopias like—you guessed it—Brave New World or Andrew Niccol’s sci-fi film Gattaca.