Three-parent babies are conceived through a specialized in vitro fertilization process that incorporates mitochondrial DNA from a third donor, potentially preventing genetic diseases from affected mothers. This technique replaces unhealthy mitochondria with those from a healthier woman, leading to a child with genetic material from three parents, and is currently being researched but not yet approved in the US. The UK has introduced laws permitting this procedure, which aims to avoid the transmission of serious mitochondrial diseases to future generations.