The year Melinda and I started our foundation, President Bill Clinton convened in the White House some of the world’s great scientists to announce a huge milestone for humanity. Two rival efforts, one led by the National Institutes of Health and the other by a private company, had completed the first draft of the human genome map. “Without a doubt,” Clinton said, “this is the most important, most wondrous map ever produced by humankind.”

Fast forward 16 years. With little public fanfare, geneticists have reached another super important milestone. While the human genome map gave us the ability to read all three billion letters of our genetic code, we now have the power to edit the human genome as well. Thanks in part to a chance discovery by researchers working to improve yogurt, scientists can now enter human cells, selectively snip out sections of code, and then incorporate new sequences permanently in the genome.

Scientists have now launched early-stage clinical trials with these new genome-editing tools. These tools are generating a ton of optimism for diagnosing, treating, and curing human disease. Even before researchers successfully complete clinical trials in humans, genome editing will be put to good use in modifying plants and animals—all of which holds big promise for our foundation’s work to alleviate hunger and improve health in poor countries.

Although I am excited about these advances, we have to approach them with caution. It’s one thing to reprogram the code that runs our computers. Reprogramming the code that runs our species is a very different thing altogether.

As with any powerful new technology, genome editing will be attractive to people with both good intentions (reducing human suffering) and bad (causing it). Even just with respect to the former, the ethical questions are enormous.

That is why I am so glad I read The Gene: An Intimate History, by Columbia University cancer doctor and researcher Siddhartha Mukherjee and recently had a chance to chat with him in person. He is the perfect person to guide us through the past, present, and future of genome science.

I loved Mukherjee’s 2015 TED Talk and his brilliant book about cancer, The Emperor of All Maladies, which won the Pulitzer Prize in 2011. It must really tick off full-time writers that a doctor can win a Pulitzer in his spare time!

In The Gene, Mukherjee once again shows his gift for making hard science easily accessible. He wrote this book for general audiences, because he knows that it’s not good enough for scientists alone to debate the huge ethical questions that their discoveries provoke. As he emphasized repeatedly in our conversation, determining the proper rules and boundaries for these technologies requires broad public discussion, debate, and consensus.

Mukherjee makes The Gene accessible in a variety of ways. Like all good science writers, he offers creative metaphors to explain difficult concepts. He is also a beautiful storyteller. He uses that talent to weave in his own family’s history of mental illness, which I found incredibly touching.  And through stories, he introduces us to the key pioneers in genetics—from Gregor Mendel, who repeatedly failed the exam to teach high school science but later ushered in the modern science of genetics, to Francis Collins, the devout Christian motorcycle enthusiast who brilliantly led the public effort to sequence the human genome.  

My favorite part of the book was the final section, “Post-Genome: The Genetics of Fate and Future.” It does a great job bringing into sharp focus the difficult ethical questions that will become increasingly intense.

Within 10 years, it will be possible for clinicians to use genome editing to help people with diseases caused by a single faulty gene, such as cystic fibrosis—an unquestionably ethical use of this new technology. But what about making the repair in egg or sperm cells to save people from developing these diseases later in life? This form of therapy could be highly effective, but it would mean that children born from these sperm or eggs would pass along their genetically modified genomes to their own children—altering the human germ line and crossing an ethical Rubicon.

Altering the human germ line is not just a hypothetical possibility. Teams of researchers in China are racing to do so in human embryos. While these researchers are using non-viable embryos, a Swedish developmental biologist recently announced that he is editing healthy, viable human embryos. He says he will not let the edited embryos develop past 14 days, but there’s no telling what other scientists may be planning. “By the time this book is published … the first ‘post-genomic’ human might be on his or her way to being born,” Mukherjee reports.

As I read The Gene, I came up with long lists of ethical questions of my own. For example, what if a prenatal test told you with a high degree of certainty that your child will have an IQ of 80 unless you do this little edit? What if a private IVF clinic offered its patients a little enhancement to their fertilized embryos to boost children’s likely IQ from high to very high? This could exacerbate inequities that are already a big problem—especially if this technology is available only for wealthy people. What about a series of edits that could dramatically reduce the incidence of disorders on the autism spectrum? Wouldn’t that mean reducing human diversity in dangerous ways—perhaps even eliminating the possibility of a future Alan Turing, the brilliant computer pioneer who helped break Germany’s Enigma code during World War II?

Technology is amoral. It is neither good nor bad. It is up to all of us—not just scientists, government officials, and people fortunate enough to lead foundations—to think hard about these new technologies and how they should and should not be used. Reading The Gene will get you the point where you can actively engage in that debate.