Genetic maternal effect refers to the influence a mother's genotype has on the phenotype of her offspring, independent of the offspring's own genotype. This occurs because the mother provides not only the genetic material but also various substances, such as proteins and RNA, during egg formation and early development. These maternal contributions can significantly affect traits like growth, behavior, and survival. In many species, including Drosophila and mice, the maternal environment plays a crucial role in shaping the offspring's characteristics. For example, the availability of nutrients and the presence of specific maternal genes can lead to variations in traits, even among genetically identical offspring. This phenomenon highlights the importance of maternal effects in evolutionary biology and development.