Why Are People Different?
If everyone's mtDNA is passed down only from their mother, then it has to be the same in everyone because it is never being mixed with any other mtDNA. Because everyone has the same mtDNA, the question arises, why are humans diverse? Well, mtDNA isn't our only type of DNA. All humans also have nuclear DNA which is passed down to offspring from the mother and father, which makes everyone a little bit different.