Three-parent babies are moving closer to reality: Researchers say that a new technique that combines the genetic material of three different people into a single embryo is safe and should result in a normal pregnancy. They published the results of their study in the journal Nature yesterday.

This technique, known as "early pronuclear transfer" and used in conjunction with in-virtro fertilization, has only been tested in the lab so far, but was approved for use last year in the UK. It was developed as a way for mothers who carry genes for faulty mitochondria to avoid passing it down to their children. Mitochondria provide energy for cells, but when they don't function properly, that can cause inherited heart, brain, and other disorders in the newborn. Now researchers who studied the embryos created with the new technique say it is safe enough to use in clinical trials.