A little over a decade ago, a clutch of scientific studies was published that seemed to show that survivors of atrocities or disasters such as the Holocaust and the Dutch famine of 1944-45 had passed on the biological scars of those traumatic experiences to their children.

The studies caused a sensation, earning their own BBC Horizon documentary and the cover of Time (I also wrote about them, for New Scientist) – and no wonder. The mind-blowing implications were that DNA wasn’t the only mode of biological inheritance, and that traits acquired by a person in their lifetime could be heritable. Since we receive our full complement of genes at conception and it remains essentially unchanged until our death, this information was thought to be transmitted via chemical tags on genes called “epigenetic marks” that dial those genes’ output up or down. The phenomenon, known as transgenerational epigenetic inheritance, caught the public imagination, in part because it seemed to release us from the tyranny of DNA. Genetic determinism was dead…

This article first appeared in The Observer on 10 October 2021. To continue reading, click here.