[Transgenerational epigenetics and its bioethical implications].

Epigenetics deals with the study of modifications that affect gene expression without altering the base composition of DNA. It can take place in a programmed way, such as the one that determines the different cellular specialties and tissues that arise during embryonic development, or it can occur randomly due to the influence of uncontrolled environmental factors, with possible consequences for health. The different epigenetic mechanisms that determine the states of activity or silencing of genes and their biological role in the regulation of gene expression, especially in higher animals, are presented. In general, epigenetic modifications are erased during early embryogenesis, so they are not transmitted from generation to generation, but their incidence during embryogenesis may be the cause of the appearance of effects that can affect health after birth, the F1 , or its offspring, F2 (intergenerational inheritance). At least in animals, transgenerational inheritance (more than two generations) has been undemonstrated until now. There is no experimental basis to support the role of transgenerational epigenetics in genome remodeling or to maintain its incidence in the evolution of species, which would mean a return to Lamarckism. We discuss the special influence of transposition, characterized by its randomness and influence on the remodeling of the genome of higher species, more in plants than in animals. Transposition is a phenomenon that influences genome remodeling, with long-term effects. We point out the myths and bioethical consequences derived from a false interpretation of the role of epigenetics as a determinant of the phenotype in the offspring of future generations.