CARL AZUZ, CNN 10 ANCHOR: A passionate debate is taking place worldwide over claims that genetically human children were recently born in China.

I`m Carl Azuz. This is CNN 10.

Here`s how the debate got started. A Chinese scientist named He Jiankui, he`s an associate professor at a Chinese university, announced earlier this

week that a pair of twin girls was born this month after their embryos were altered to make them resistant to human immunodeficiency virus or HIV.

Their parents, according to Professor He, volunteered for the experiment. The father is believed to carry HIV.

Professor He also appeared to suggest that a third genetically modified baby is possible that the pregnancy is in the early stages.

How could this be done?

Professor He claims to have used CRISPR, a genetic editing tool, to alter the twins` DNA. Researchers say CRISPR makes it possible to change a

particular part of someone`s genome, or delete a gene altogether.

But the idea of a genetically edited child is highly controversial. For one thing, some scientists doubt this even happened. The research hasn`t

been independently confirmed. For another, American biologist and Nobel Prize recipient David Baltimore says genetic editing is irresponsible until

it`s proven to be safe and effective, and it hasn`t yet. Baltimore also says genetically modifying someone to be resistant to HIV isn`t necessary

since there are other treatments available for the disease that attacks the immune system.

A group of Chinese scientists spoke out against the research, suggesting that experimenting on a human is unethically and crazy. And there are

concerns about the consequences of gene editing. A scientist who helped invent CRISPR says when you change one thing, something else gets changed

too, and it`s not known yet what kinds of effects this could have on the Chinese twins.

For his part, the associate professor says he`s proud of his alleged achievement because the parents had, quote, lost hope for life, but now,

the father plans to work hard and take care of his wife and two daughters.