Members of the medical community admonished Chinese scientist He Jiankui after he announced last week that he had used the gene-editing tool CRISPR to edit babies' genes.

At an international gene-editing summit in Hong Kong, Jiankui said he had modified the genes of twin baby girls to protect them from contracting HIV.

The consensus among bioethicists is that practicing gene-editing on humans is still extremely dangerous and unethical. Art Caplan, director of the Division of Medical Ethics at NYU Langone Medical Center, told Boston Public Radio Thursday that Jiankui’s actions were “not appropriate.”

“We don’t know what we are doing, is the short answer to why this shouldn’t be done. The technique of gene editing, CRISPR, and some other tricks that we can use to scissor out bad genes and put in good ones is really pretty novel. It has been around a few years, but people are basically perfecting it. You don’t want to put a children at risk of having problems by trying to do it in an embryo when we don’t know how to do it in a cell,” Caplan said.

Genetic editing could have unknown side effects, Caplan said, that could cause birth defects and even death. Southern University of Science and Technology in Shenzhen, China, where Jiankui works, released a statement condemning his work and announcing an investigation into the incident.