The twins you're referring to, Lulu and Nana, were reportedly born in China in 2018. They were the subject of significant controversy due to the claim by Chinese scientist He Jiankui that he had used CRISPR-Cas9 gene editing technology to modify their genomes to confer resistance to HIV by disabling the CCR5 gene. He Jiankui's announcement sparked international condemnation and raised numerous ethical concerns regarding the use of gene editing technology in humans, particularly in the context of inheritable genetic modifications.

The use of CRISPR-Cas9 in this case was widely criticized for several reasons:

Lack of Transparency: He Jiankui's work was not conducted transparently, and it was revealed that the participants in the study were not adequately informed of the risks involved.

Ethical Concerns: Editing the human germline (cells that can be passed on to future generations) raises profound ethical questions, as any unintended consequences or off-target effects could be inherited by future generations.

Safety Concerns: The long-term effects and potential unintended consequences of gene editing in humans are still largely unknown. CRISPR technology is still in its early stages, and there is a risk of unintended genetic mutations or other adverse effects.

Following the revelation of his work, He Jiankui faced widespread criticism and was reportedly placed under investigation by Chinese authorities. The incident prompted calls for stricter regulations and oversight of gene editing research, particularly in the context of human germline editing. The case of Lulu and Nana serves as a cautionary tale regarding the ethical, social, and scientific complexities surrounding the use of gene editing technology in humans.