Why is mitochondrial DNA inherited only through the mother?

Previously, researchers believed that maternal inheritance was orchestrated by processes in the mother’s eggs. Large structures called autophagosomes are known to engulf the paternal mitochondria shortly after the sperm enters the egg.
However, the researchers identified a gene called cps-6, which turned out to initiate the breakdown process in the mitochondria in a mother-like manner. They found that removing cps-6 caused the fathers mitochondria to stay longer in the embryo. It also led to higher rates of fetal death.