Stanford University has started a review of interactions that some faculty members had with He Jiankui (HUH JEEN-qway), the Chinese scientist who claims to have helped make gene-edited babies.

A school official said Thursday a review is underway.

Several professors including He’s former research adviser have said they knew or strongly suspected He wanted to try gene editing on embryos intended for pregnancy.

The work has been widely criticized since November, when He revealed the births of twins whose DNA he said he altered. Most scientists think gene editing for reproductive purposes is too risky to be tried yet because of the danger of harming other genes and because the DNA changes may be passed to future generations.