NPR recently ran an article on the latest developments in the area of “three-parent embryos.” Such embryos are being created in an effort to help those who carry a genetic defect in their mitochondrial DNA.

The article is a long and at times technical read, but the upshot is that there is much scientists do not know, much they cannot predict, and yet many are pressing ahead anyway.

The bottom line, according to biologist David Rand of Brown University, who studies mitochondrial genomes, is that when you swap mitochondria, the reaction is “highly unpredictable.”

And that’s why many experts are calling for caution even amid all the excitement following the three-parent Mexico trial — though there is reason to believe they aren’t being heard.

I would go even further than calling for caution. I would call for an immediate and total halt to this experimentation.

Let’s list the ways we know this can — and will — go wrong.

This technique relies on egg donors, and we have done a great deal of work exposing the problems with egg donation.

It creates human embryos for destruction. One proposal expressly calls for only male embryos to be transferred for possible pregnancy, meaning the female embryos would be . . . well, we’re not told. But the options are indefinite frozen storage or destruction.

In this selection process we see the prospect of eugenics, that is, screening to select just the right egg donors, screening to select only the correct embryos.

And these changes will affect not only the embryo and resulting child being created, but also that child’s children, and so on.

Doug Wallace, the head of the Center for Mitochondrial and Epigenomic Medicine at the Children’s Hospital of Philadelphia says that this “could mean a therapy that might change the DNA of tens of thousands, maybe hundreds of thousands, of babies conceived by this method. That would have a real impact on the long-term future of society, Wallace adds, and we don’t yet fully understand all of the implications.”

Let that sink in.

Caution simply is not enough. Primum non nocere. First, do no harm.