Professor Azim Surani, a leading developmental biologist and geneticist at the University of Cambridge, adds that while there is good evidence that epigenetic inheritance happens in plants and worms, mammals have very different biology. Surani’s lab carried out thorough studies on how epigenetic information was erased in developing mouse embryos and found that “surprisingly little gets through” the reprogramming process.

Professor Timothy Bestor, a geneticist at Columbia University in New York, is far more damning, claiming that the entire field has been grossly overhyped. “It’s an extremely fashionable topic right now. It’s very easy to get studies on transgenerational epigenetic inheritance published,” he says, adding that all this excitement has lowered critical standards.

It’s early days yet in the understanding of the role of epigenetics in disease and behavior, and there’s a lot left to be learned. There is now a wealth of experimental literature on cells as well as a variety of laboratory species, demonstrating some of the mechanisms of gene regulation that involve epigenetic changes of DNA. There are carefully done experimental studies that show multi-generational transmission of such changes. There have also been epidemiological and even experimental studies of intra-uterine or maternal experience affecting things like body weight in offspring. Thus, even without specific epigenetic data at the genome level we have every reason to expect that life experience at any age could affect even complex traits. And what would be more likely than some sort of epigenetic mechanism to be responsible?

One should also keep in mind that trans-generational correlation can look very much like regular genetic transmission and make a trait look ‘genetic’ in the classical sense, rather than in the epigenetic sense.

It clearly befalls those advocating, and those dismissing, epigenetic inheritance to keep their powder dry until we can see more clearly into the whites of the genome’s eyes…