What mode of inheritance refers to traits passed only from the mother and affects both males and females?

Mitochondrial inheritance is a mode of inheritance where traits are passed exclusively from the mother to her offspring. This is because mitochondria, which are the energy-producing units within cells, are inherited maternally; the sperm does not contribute any mitochondria to the offspring during fertilization. As a result, any genetic mutations or traits located within mitochondrial DNA can affect both male and female children equally.

In contrast, autosomal inheritance involves genes located on the autosomes (non-sex chromosomes), where traits can be inherited from either parent and can affect both sexes. X-linked inheritance pertains to genes found on the X chromosome, which can result in traits being expressed differently in males and females due to the presence of one X chromosome in males and two in females. Y-linked inheritance, on the other hand, involves genes on the Y chromosome and is passed from father to son, thus affecting only males. Therefore, mitochondrial inheritance is unique in that it is strictly maternal and impacts both genders equally.