Certain genes have apparently unusual inheritance patterns. for instance, in the mouse autosomal gene h19, only the copy inherited from the mouse's mother is expressed. conversely, in the mouse autosomal gene igf2, only the copy inherited from the mouse's father is expressed. the consequence of this is that imprinted genes are expressed as if they were present in only one copy, even though there are two copies of each of these genes in each cell. what process or processes are responsible for this phenomenon

Epigenetic inheritance

Explanation:

Epigenetic inheritance are the processes by which heritable modifications in gene function occur but are not due to changes in the base sequence of the DNA of the organism. Examples are paramutation, X-chromosome inactivation, and parental imprinting.

This case is the example of parental imprinting which is an epigenetic phenomenon in which the activity of a gene is dependent on whether the gene was inherited from the father or the mother. Some genes are maternally imprinted, others paternally.

the answer to your question is sperm