The possibility of storing hereditary information outside DNA genome molecules is discussed. A hypothesis of epigene as a unit is put forward. According to this hypothesis: a) hereditary information is coded for not only by the sequences of DNA nucleotides, but also by other means such as the presence or absence of some regulatory proteins; b) storage of hereditary information during the cell life cycle is provided by the feedback mechanism; c) the information inherited from parents to offspring is transmitted through the distribution of extragenomic macromolecules of regulatory substances. Models of the simplest systems with epigenic properties are considered. Depending on the concrete state of epigenes observed in different states and individual ontogenetic patterns, intercrosses may produce the following effects: 1) absorption (offspring will have epigenes in similar states; 2) formation of epiheterozygotes yielding gametes of various kinds; 3) formation of variants each reproducing gametes of only one kind and the variants producing different kinds of gametes. To detect epigenic effects the special interbreeding experiments are suggested.