What genes are inherited from the mother only?

Mitochondrial DNA (mtDNA) is inherited exclusively from the mother. Unlike nuclear DNA, which is a combination of genetic material from both parents, mitochondrial DNA is passed down solely from the mother to her offspring. This is because the mitochondria, which are the energy-producing organelles in cells, contain their own small amount of DNA.

During fertilization, the sperm contributes its nuclear DNA to the offspring, but the mitochondria from the sperm are typically discarded, while the mitochondria from the egg (which came from the mother) are retained. As a result, the genetic information contained in the mitochondria, including any mutations or variations, is maternally inherited and passed down from one generation to the next along the maternal lineage. This unique mode of inheritance is useful in various genetic and anthropological studies, as it can be used to trace maternal lineages and study evolutionary relationships.