Definition of Maternal Effect
The maternal-effect is a pattern of inheritance for a limited number of nuclear genes in which the phenotypic traits of the offspring are directly determined by the genotype of the mother. These effects are known to be transgenerational epigenetic effects that cause heritable variations among the individuals for some reasons other than genetic differences. The zygote is formed by the fusion of male and female gametes.
The size of the female gamete is big and its cytoplasm is composed of certain factors that impart specific effects on the developing embryo. The traits of the offspring are due to nuclear and mitochondrial DNA. Maternal inheritance is due to the expression of genes by mitochondrial DNA whereas the phenotypes that are controlled by the factors submerged in the cytoplasm of the female express a maternal effect.