Yup. A small number of genes only need/want one functional copy for some reason or another. Gene imprinting comes in by deactivating one copy of the gene. I think the critical period is during gametogenesis. The genes are "wiped clean" and then imprinted. In humans, genes are imprinted by base methylation. Some genes are preferrentially imprinted in the male contribution, other genes preferrentially imprinted in the female oocyte. Once the zygote forms, the offspring will have one normal, active copy of the gene, and the other imprinted and deactivated.
If a gene is preferrentially deactivated on the male-contributed chromosome, only the allele coming from the maternal gene is expressed.
