Throughout my extensive career reporting on extraordinary breakthroughs in biology, I’ve observed numerous concepts gaining massive attention, receiving thorough media scrutiny for years, and later fading from the public consciousness. Take, for instance, human cloning.

Following the landmark birth of Dolly the sheep in 1997—the first cloned mammal—speculation soared about the potential for human cloning. There were even some implausible claims about human clones existing. Yet, in recent years, such fervor has significantly diminished.

Nonetheless, reproductive technologies have evolved remarkably since the 1990s. Notably, just six years after CRISPR was unveiled, the world saw the first unlawful creation of a gene-edited child. This raises questions about what might be occurring behind closed doors. Are human clones already out there, undetected? Of course, identical twins don’t count.

What could motivate someone to engage in this? Recently, in a discussion between Vladimir Putin and Xi Jinping, the topic of extending life via organ transplants emerged. The most effective method could involve cloning individuals for organ harvesting, thereby eliminating the common issue of immune rejection often depicted in science fiction narratives. Consider Island or the book Never Let Me Go.

Moreover, cloning brings forth the notion of creating a duplicate of a person, offering a semblance of immortality, as illustrated in the television series Foundation, where the empire is governed by successive clones. However, our experiences with identical twins tell us that sharing the same genome does not equate to being the same person. As shown by Tatiana Maslany in the series Orphan Black, each clone evolves into a distinct individual. Nevertheless, wealthy individuals can hold irrational beliefs similar to others and often display a particular desire to extend their lifespans.

For scientists, there’s also the allure of being the first to achieve a groundbreaking feat. A report from a Chinese commission determined that the creators of CRISPR children “conducted research illegally in pursuit of personal fame and profit.”

Goals of Therapeutic Cloning

So, could human clones exist? For many years, the notion of cloning mammals was deemed unfeasible. Early embryo cells have the ability to differentiate into any bodily part but quickly become specialized—a process previously thought irreversible.

Dolly’s existence disproved that theory. She was produced by fusing cells from an adult ewe’s udder with a DNA-depleted egg. Her announcement in February 1997 led to a frenzy of attempts to generate cloned human embryos. The objective wasn’t to create cloned infants, but rather to harvest embryonic stem cells for novel medical therapies. As cloned cells are a perfect match for an individual, they could theoretically be employed to produce replacement tissues and organs with no risk of immune rejection.

However, extracting stem cells from cloned human embryos has proven more challenging than anticipated. It wasn’t until 2004 that Hwang Woo-seok claimed success. At that time, I found his paper impressive, as it addressed all conceivable objections effectively. Unfortunately, the study was later revealed to be fraudulent, resulting in its retraction. This experience remains ingrained in my memory. Nowadays, whenever a thesis appears too good to be true, my initial instinct is to be skeptical.

Ultimately, true embryonic stem cells from cloned human embryos weren’t obtained until 2013. By then, alternative methods for generating compatible stem cells through the activation of specific genes had emerged, leading to a decline in interest in therapeutic cloning.

Cloned Pets and Other Animals

Conversely, animal cloning has become increasingly established. Occasionally, headlines emerge when celebrities disclose that they’ve cloned their pets. Recently, former NFL player Tom Brady made news by revealing that his dog is a clone, produced by a company acquired by Colossal Biosciences.

Apart from serving as a way to “revive” cherished pets, cloning is also utilized in agriculture and horse breeding. For instance, male horses are often castrated, meaning that if they excel in show jumping, the only method to utilize their genetic material for future breeding is through cloning.

Nonetheless, animal cloning continues to pose significant challenges. A 2022 study of the first 1000 dog clones found that the cloning process is still highly inefficient, with merely 2 percent of implanted cloned embryos resulting in live births. This inefficiency contributes to the high cost of pet cloning, around $50,000.

Moreover, about 20% of cloned dogs presented noticeable physical anomalies, including enlarged tongues, unusual eye colors, cleft palates, and excessive muscle mass. Some male dog clones even exhibited female physical traits.

But what if the wealthy and powerful could clone themselves, unburdened by such concerns?

Challenges in Adult Cloning

Multiple sources have indicated several successful monkey cloning endeavors since 2017, suggesting potential applicability for humans as well. However, these sources often fail to mention that all these primate clones have been derived from fetal cells, not adult ones.

The crux of the issue lies in the fact that reprogramming adult cells to mimic a fetal state is far more complex than reprogramming fetal cells. To me, cloning signifies creating a genetically identical replica of an adult, which is what made Dolly’s achievement exceptional.

In essence, I remain convinced that cloning an adult is still unattainable. In a world filled with dictators and eccentric billionaires, this might be a fortunate circumstance.