Mitochondrial Replacement Therapy (MRT) is a special medical technique used to prevent certain diseases from being passed from a mom to her baby. These diseases are caused by problems in tiny parts of our cells called mitochondria, which help produce energy. Sometimes, the mitochondria can have defects, making people very sick.
Scientists have come up with a way to give babies healthy mitochondria and prevent these diseases. They take the mom's egg (which has the bad mitochondria) and remove the nucleus (which is like the main library of all the body's instructions). Then, they put this nucleus into another woman's egg, which has healthy mitochondria but no nucleus. This creates a new egg that has healthy power plants (mitochondria) and still carries all the family traits (from the nucleus).
These issues mean we have to think carefully about how we use MRT, balancing the good it can do against these tricky questions.