Like the parent comment said, it's a rabbit hole...

Some genes only remain epigenetically modfied untill the next cell division, others take multiple rounds, and still others can remain for 1-3 generations based on whether it was the father or the mother that carried the epigenetic modifications.

Simple example would be the Barr-body in women: most of the genes on one of the X-chromosomes in women get turned off shortly after germination - to keep the gene products balanced. But these modifications get reverted before one of the X-chromosomes can end up in an egg.

There is a lot about epigenetics we don't really understand but it seems extremely complex and setting up conclusive experiments is extremely difficult.