How a third parent's DNA can prevent an inherited disease

Scientists can protect children from being born with certain devastating genetic disorders by creating "three-parent" babies, according to the results of a landmark study released Wednesday.

British researchers used the experimental technique to help families have eight children who appear healthy. They now range in age from younger than 6 months to older than 2 years.

The families have been plagued for generations by rare but often fatal inherited mitochondrial disorders, according to two papers published in The New England Journal of Medicine.