What does epigenetics study?

"The modern term epigenetics has multiple related meanings. Firstly, it denotes heritable — via mitosis and/or meiosis—changes in gene function without changes in DNA sequence. Secondly, epigenetics refers to the study of those processes and mechanisms and their implications for biological functioning. To avoid misunderstandings, this introduction sometimes uses terms such as ‘epigenetic mechanisms’ when referring to the first sense of the word and phrases such as ‘epigenetic research’ and ‘epigenetic knowledge’ in the context of the second sense. This introduction will provide some scientific background on aspects of epigenetics that are relevant to ethical discussions. Epigeneticists do not study changes in DNA itself but rather mechanisms that influence how and when genes—which are stretches of DNA bases—are expressed in an organism. Epigenetic mechanisms can affect the transcription and translation"