Epigenetics in prokaryotes

No, not necessarily. Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence is called epigenetic inheritance. In flies, for example, experiments have suggested that a particular histone-modifying enzyme recruits a DNA methylation enzyme to one region and that the two enzymes collaborate to silence a particular set of genes.

Epigenetic variations might help explain why one identical twin acquires a genetically based disease, such as schizophrenia, but the other does not, despite their identical genomes. Alterations in normal patterns of DNA methylation are seen in some cancers, where they are associated with inappropriate gene expression. Evidently, enzymes that modify chromatin structure are integral parts of the eukaryotic cell's machinery for regulating transcription.

ANYWAYS, in a nut-shell, epigentics is when DNA is modified using the addition of methylated groups to nucleotides or the addition of acetyl groups. It is not a change in the actual sequence.