It is a grave ethical misstep for a scientist to manipulate the genetic code of human embryos, as Chinese researcher He Jiankui claims to have done, he says, to make them resistant to infection by the HIV virus.
Not only because the technology is untested, and editing one piece of human DNA may well have unanticipated effects in another part of the genome.
Not only because these techniques, if perfected, can be exploited to enable the privileged few to rig their heredity, amplifying advantages that wealth already delivers and allowing mothers and fathers to tinker with everything from a child’s eye color to his or her likelihood of suffering from clinical depression.
Especially chilling about the profound risks of rigging biological source code is that once edits are made, they get carried from parent to child and grandchild and great-grandchild, modifying humanity in ways that are essentially undetectable and can never be undone.
Far be it from us, as technology advances, to rule out the possibility of ever allowing human DNA to be tweaked in vitro. If we have the means to forever extinguish congenital diseases that cause excruciating pain and early death, would we really leave such a tool on the table?
But such power must be used in the rarest of circumstances, under the strictest controls, only after vetting all hazards to individual humans and humanity at large have been.