We now know that almost every characteristic of our human bodies, from our appearance to our athletic abilities to many of the diseases we’re prone to, is largely determined by our genes—our DNA (and related molecules). Even before we knew that, we were able to breed desirable traits into our livestock and agricultural crops and some of us wondered whether doing the same thing with humans would be a good idea. So what if we could just take a pair of scissors and some Scotch tape to someone’s genome and, with a snip here and a careful patch there, cure their cancer? An enzyme technology known as CRISPR/Cas9 may offer something very close.

That was one of the big science news stories of the past week. Scientists in China have begun clinical trials in humans using CRISPR to treat cancer patients by “editing” their genes. There’s a kind of loophole in our immune system that cancer takes advantage of—closing that loophole should help our bodies prevent the growth of cancer more efficiently, and that can be done by altering genes in a certain type of immune system cell. So far, so good, right?

The scissors analogy for CRISPR is a good one—researchers chemically break a strand of cellular DNA in a desired spot, perhaps remove some pieces, then allow the DNA to come back together again. It’s also possible to splice a patch of new laboratory-made DNA into the break. Since DNA is a critical part of the instructions that tell our cells to do what they do, gene editing changes the behaviour of the cell and its components. That’s the whole point.

Although the genes of the human body have been mapped, we still have a huge amount to learn about which genes are responsible for which human characteristics, exactly how they produce the effect, and what the implications will be if we make changes. The long-term side effects are especially hard to predict—we can’t know until we try it, which means experimenting on humans.

This prospect might fill you with horror or with wonder. It might conjure up images of Frankenstein or of beautiful, nearly-immortal super humans. As is the case with almost every technology, it will be up to us to decide how much of it is a good thing, and which directions we don’t want to take it. A method similar to CRISPR has already been used to cure a girl of leukemia, and it may soon be used to battle muscular dystrophy, HIV, and retinitis pigmentosa (a major cause of blindness). Certainly curing cancer sounds like a tremendous benefit. Many other hereditary health conditions are potential targets for gene editing. But what if curing diseases isn’t enough? What if it’s used to help women (or men) stay as slim as a supermodel? Or to produce champion swimmers with webbed toes? Or to enhance a child’s language skills at the expense of their math abilities? I especially believe (and fear) that gene-editing will at some point be used to alter our bodies into whatever body image is currently in fashion. Let’s face it, we live in a consumer society. Eventually, the characteristics of our own bodies will become a “product” for which we’ll be able to pay. And the prospect of changing our bodies at will opens up a huge number of potential ways we could be manipulated and exploited by governments, corporations, or both.

I’m not a fear monger—gene editing probably has just as much potential for good as for bad. My point is something I’ve said before: all of us have a responsibility to stay informed and to speak out about how powerful technologies are used. One thing we can’t do is to put the genie back in the bottle. That never works. Gene editing is here to stay. But let’s be proactive and say, “Wow, where can we go with this?” Instead of, “OMG! Where did that come from?” Let’s get ahead of developments and work out the rules our society wants researchers to follow, instead of just reacting after the fact.

To learn more, here’s a good interview with prominent CRISPR researcher Jennifer Doudna.