When are parental imprints established?

Imprints are established during the development of germ cells into sperm or eggs. After fertilization, the embryo they are maintained as chromosomes replicate and separate in the growing organism. The embryo also becomes diploid. However, in the germ cells of the new organism, imprints are erased early on only to be re-established later in germ-cell development. This completes the imprinting cycle. In somatic cells, imprints persist and undergo modifications during development. These imprints need to be interpreted or "read." Reading involves translating methylation or chromatin imprints into differential gene expression. This process results in expressions favoring one parental allele over the other.