Ever since Darwin formulated his theory of evolution, it has been assumed that genetic variation is a product of random events (mutations), providing the only basis for natural selection. However, recent advances in our understanding of how the genome is regulated suggest that information may also be passed from the environment to the genes, allowing individual experiences to be transferred into altered gene expression. It has also been demonstrated that such acquired genetic modifications can be transferred to the offspring, opening previously unknown pathways for evolutionary adaptations. In this review, such effects, their possible mechanisms, and their implications for applied ethology will be discussed, using examples from various experiments, including those from my own group. For example, it has been shown that stressful events in plants, chickens, rodents and humans can modify the phenotype of the exposed individuals and their offspring in more than one generation. Primary mechanisms appear to be chemical modulation of DNA (methylation) and histones (acetylation), but also RNA interference and other regulatory factors have been implied. Common mediators could be steroid-hormones, which respond to stressful experiences of an animal. This may have large implications for our understanding of how animals have adapted during domestication. For example, animals may have been inadvertently selected for their ability to modify gene expression across generations (“evolvability”), suggesting that domesticated populations may be able to respond more rapidly to environmental challenges. Furthermore, although stress is associated with poor welfare of the affected individual, it may perhaps allow offspring to adapt better, hence improving long-term welfare in future generations.