Mitochondrial DNA (mtDNA) is in mitochondria within eukaryotic cells. In most multicellular organisms, mtDNA is inherited from the mother.  In sexual reproduction, the mitochondria in mammalian sperm are usually destroyed by the egg cell after fertilization. The reason for this include consider an egg contains on average 200,000 mtDNA molecules, whereas a healthy human sperm was reported to contain on average 5 molecules. Thus it is expected that mtDNA is inherited from the mother.