In genetics, paternal mtDNA transmission and paternal mtDNA inheritance refer to the incidence of mitochondrial DNA (mtDNA) being passed from a father to his offspring. Paternal mtDNA inheritance is observed in a small proportion of species; in general, mtDNA is passed unchanged from a mother to her offspring,[1] making it an example of non-Mendelian inheritance. In contrast, mtDNA transmission from both parents occurs regularly in certain bivalves.