Answer:
Hermia is basically saying they were made to be together.
There are three main differences between nuclear and mitochondria DNA (mtDNA): 1.) mtDNA is circular, whereas nuclear DNA is linear. (Both are double stranded) 2.) mtDNA is (generally) uni-parentally inherited, in most animals (not mussels though for example), mtDNA is passed from mother to offspring. from wiki
Is it the background of the story? Prequel? Maybe? Idk