Research on mitochondrial epigenetics is providing new insights into doubly uniparental inheritance in bivalves. Studies on various species, including mussels and clams, are examining the presence and function of male mitochondria in somatic tissues and the distribution of mitochondrial DNA methylation. The findings appear to vary across species, with some exhibiting doubly uniparental inheritance and others showing no evidence of this phenomenon despite mitochondrial heteroplasmy.