We're Already Designing Babies

ASPEN, Colo.—A new type of in-vitro fertilization procedure allows doctors to transfer the mitochondrial DNA from one woman into the egg of another, effectively creating a baby with three parents: The father, the egg mom, and the mitochondrial mom. The method is intended for a tiny fraction of women who have what's known as a "mitochondrial disease," which increases the likelihood of bearing children with severe birth defects.

Both the U.K. and U.S. are currently debating permitting clinical trials for the technique. As the New York Times described in a recent story:

In Britain, national law prohibits altering the germ line, but Parliament is very likely to vote later this year on whether to allow mitochondrial replacement to move forward. Likewise, this February, the F.D.A. held a meeting to examine the possibility of allowing clinical trials. If either gives the go-ahead, it will be the first time a government body expressly approves a medical procedure that combines genetic material of three people in a heritable way.

Many find the mitochondrial procedure morally questionable because of how close it...