An FDA panel is currently reviewing a procedure that would allow a child to inherit genetic material from three different people.
If that sounds like one too many to you, congratulations! Your moral intuition is more highly developed than that of many scientific researchers.
The procedure, pioneered at Oregon Health and Science University, involves replacing defective mitochondria in a woman's egg with healthy mitochondria from another woman.
To understand the controversy, you have to understand that every human carries two kinds of DNA: chromosomal DNA, the iconic "double helix," to which both your father and mother contribute equally, and mitochondrial DNA, which serves as the power source in cells and is only passed on by your mother.
If this proposed procedure is approved, the result would be children with DNA from three different people.