Three years ago, CheMyong Jay Ko received a call from a distraught older man. Ko, a professor at the University of Illinois at Urbana-Champaign’s College of Veterinary Medicine, listened as the caller told him that his dog had just rushed into traffic and been struck by a truck, killing it immediately. He had called Ko with a simple but urgent question: Would it be possible to clone his beloved pet?

For Ko, the call wasn’t as peculiar as you might think. After all, he has studied genetics and cloning for genetics and physiology for more than 20 years. So he had a ready answer: yes, cloning was possible.

Naturally, there was a catch. Cloning requires cells that contain enough intact DNA. But animal tissue begins to degrade soon after death as bacteria start to gnaw away at newly defenseless cells. Ko knew that they had to act quickly if they were going to have a chance to preserve the animal’s genetic material. He and two of his students piled into a van and drove an hour to the man’s home, where they took skin cells from the recently deceased pup.

Back in the lab, he and his team revived and cultured some of the cells from their samples. Theoretically, they now had the material to create a genetic double of the dead dog. In practice, of course, things were about to get a lot more complicated.

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Scientists have known that mammal cloning was feasible since 1996, when Dolly the sheep was born. Since then, they quickly moved on to trying to other animals: mice, cattle, pigs, goats, rabbits, cats. But due to differences in the canine reproductive process, dogs proved a trickier challenge.

After several failed attempts, the first successful experiment in dog cloning took place in 2005, when a South Korean team managed to produce a pair of Afghan hound puppies from the ear-skin of a dog named Tai. One of the newborns died soon after, of pneumonia. But the second cloned dog, which the team named Snuppy, lived for an impressive 10 years. Snuppy was deemed a “revolutionary breakthrough in dog cloning” and one of the most amazing “inventions” of the year by Time magazine. Ko was an adviser on the South Korean team.

At the time, researchers were debating whether cloning produces animals that age faster or have higher risks of disease compared to their cell donor. Dolly died at 6, around half the age of the average sheep, from lung disease and arthritis; Snuppy died of the same cancer that had killed Tai at age 12. In 2017, The South Korean team explored this issue in a paper in Nature on their attempt to produce clones from Snuppy’s own stem cells. Their ongoing research hopes to “study the health and longevity of cloned animals compared with their cell donors.”

The science of dog cloning has advanced considerably since the researchers first presented Snuppy to the world. Today, there are a handful of commercial companies and institutions, many of them located in South Korea, committed to bringing cloning to ordinary pet owners—for a price. One of them, the United States-based Viagen, charges $50,000 before taxes, paid in two installments, to clone your dog. (In case you were wondering, they also clone cats, for $25,000).

Ultimately, Ko’s anguished septuagenarian didn’t end up cloning his dog after all. According to Ko, it was the price that turned him off. (For now, his dog’s cells are still sitting in a freezer, unused but theoretically still useable, should he change his mind.)

But many wealthy pet owners are willing to shill out for these rarefied services. No doubt the most famous is Barbara Streisand. Last month, the singer and filmmaker shocked the Internet when she told Variety that two of her three dogs, Miss Violet and Miss Scarlet, had been cloned from cells taken from the mouth and stomach of her fluffy, white, recently deceased Coton de Tulear, Samantha. Samantha, or Sammie, had passed away the previous May.

As Streisand wrote a few days later, in an op-ed in the New York Times:

I was so devastated by the loss of my dear Samantha, after 14 years together, that I just wanted to keep her with me in some way. It was easier to let Sammie go if I knew I could keep some part of her alive, something that came from her DNA. A friend had cloned his beloved dog, and I was very impressed with that dog.

If you spend enough time reading about pet cloning, you’ll see that adjective come up over and over again: beloved. When people clone their animals, they do so because they love them—and because they can’t stand the prospect of losing them forever. The average American dog lives between 7 and 15 years. With that perspective, the price may seem more reasonable. What is $50,000, if it saves you the immeasurable pain of saying goodbye to a beloved family member?

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Talk to experts about what cloning actually entails, however, and you’ll begin to realize that the costs are steeper than most realize—and go far beyond money.

“I understand the impulse behind trying to keep your dog in perpetuity,” says Alexandra Horowitz, head of Columbia University’s Canine Cognition Lab and author of the 2010 book Inside of a Dog: What Dogs See, Smell, and Know. “One of the great sadnesses about living with dogs is that the time we live with them is so short. Unfortunately, you have to overlook a huge amount about the process—to say nothing about what cloning actually is—to be satisfied with the results.”

The process of cloning is simple enough. It begins with cultured cells, like those Ko retrieved from his bereaved caller’s former companion. Next, scientists extract unfertilized eggs from another, unrelated dog, removing them from its fallopian tubes. That animal generally isn’t harmed, though the procedure is invasive.

“We take the eggs out and bring them into the laboratory. There we manually remove their nucleus,” Ko says. “We can use a fine pipette needle to remove [them] and suck the nucleus out.” (Think of sucking a boba pearl out of milk tea with a straw.) This process strips the eggs of the genetic material that they contain, making the egg cell essentially a blank slate for scientists to fill with DNA of their choosing. Scientists can also achieve a similar effect with a targeted blast of ultraviolet light, which destroys the genetic material.

Scientists then take one of the cultured somatic cells from the animal that they’re seeking to clone and carefully insert it into the egg with a needle. In a Frankensteinian twist, they hit the composite egg with an electric burst that “fuses” the two together.

“Through that, the nucleus from the donor cell will become part of the egg,” says Ko. “Now the nucleus from the donor cell will behave like the nucleus of the egg.” There’s one critical difference. Unlike an unfertilized egg, which has half of the necessary genetic information to make a new life—the other half is in the sperm cell—you already have a full set of genetic information, just as you would in a viable embryo.

The electrical burst also jumpstarts cell division. After a few days, assuming that the process successfully takes hold, the lab can then surgically implant the cells into yet another animal: a surrogate dog mother. Treated with hormones, and sometimes made to “mate” with vasectomized male dogs, these surrogates can, under ideal circumstances, carry the pregnancies to term. Often, surrogates then go on to carry other cloned pregnancies.

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If you were ever considering cloning your dog, this process may already have you hesitating. But things are about to get even more questionable, morally.

Even not counting the original egg donor and surrogate, the cloning process still requires numerous dogs to produce a single clone. Consider: Many cloned pregnancies don’t take hold in the uterus or die shortly after birth, as was the case with Snuppy’s twin. Snuppy and his twin were two of only three pregnancies that resulted from more than 1,000 embryos implanted into 123 surrogates.

“You need a good number of dogs to do this type of cloning,” Ko acknowledges, though he adds that the success rate has gone up in the intervening years. “I would say it’s about 20 percent. Very high.”

As Ko and his co-authors note, there may be legitimate reasons to clone animals. For instance, you might want to make many of the same dogs for research, replicate service dogs with rare and desirable abilities, or clone endangered species for conservation. Yet many animal advocates and ethicists still raise strong objections. “The process of cloning basically creates an industry of what I think of as farmed dogs,” Horowitz tells me.

Bioethicist Jessica Pierce has also argued against the practice, writing in the New York Times that the cloning industry has produced “a whole canine underclass that remains largely invisible to us but whose bodies serve as a biological substrate.”

Even if one is willing to overlook the suffering of animals harvested for their eggs and co-opted into pregnancy, questions still arise. Key among them may be what pet owners think they’re getting when they clone a “beloved” animal.

Centuries of selective breeding have left many with the misconception that a dog’s genetic makeup determines its personality. “In a way, cloning companies are preying on this ignorance, if you will, about what’s actually going on scientifically,” Pierce tells me over the phone. “And that’s unfortunate. Unethical.” Genetic preservation companies feature names like "PerPETuate, Inc." which would seem to imply the indefinite continuance of the cloned animal.

Horowitz agrees. “There might be some breed tendencies, and there certainly are tendencies that a genome will avail that makes a cloned dog maybe likelier than some other non-genetically similar dog to do a kind of thing,” she says. “But everything that matters to us about the personality of a dog is not in those genes. Everything is in the interaction of that genome with the environment, starting from the time they’re in utero—just as with humans.”

For those who love the dogs they’ve lived with, this should be a critical point. You adore this animal—not because of its genetics, but because it became the creature that it is through time spent with you. While a clone may perfectly replicate its genome, it won’t be the same dog because it won’t have the same life, a life that it lived in your company. In almost every way that matters, then, they’re different dogs.

Even Streisand implicitly admits as much, telling Variety that her two cloned pups “have different personalities” than Samantha—and, presumably, each other. “Each puppy is unique and has her own personality,” she writes in the Times. “You can clone the look of a dog, but you can’t clone the soul.” The jury is out on the ethics of what she did with her dogs, but on this point, she’s right.