Differential expression of same gene depending on parent of origin is referred to as

It has now been established that functional differences exist between the paternal and the maternal copies of some genes. These differences arise from an epigenetic process called genomic imprinting, whereby ceain genes are differentially "inactivated" during paternal and maternal gametogenesis. Maternal imprinting refers to transcriptional silencing of the maternal allele, whereas paternal imprinting implies that the paternal allele is inactivated. At the molecular level, imprinting is associated with methylation of the gene promoter, as well as related events such asmodification of DNA-binding histone proteins, the sum total effect of which is to silence the gene. (Robbins Basic Pathology,9th edition,pg no. 243)