transgenerational inheritance

Normally, when we think of something passing from parent to child, we mean the DNA sequence. Transgenerational epigenetic inheritance asks whether something else can be passed too: an epigenetic state, such as a pattern of marks, that affects offspring across several generations without any change to the DNA itself.

The bar for true transgenerational inheritance is high. A signal must survive not just into the children but into grandchildren and beyond, in individuals who were never directly exposed to the original trigger. This rules out simpler explanations where a pregnant individual and the developing fetus and even its germ cells are all exposed at once.

The challenge is that mammals largely erase and reset epigenetic marks twice, once in the germ cells and once in the early embryo. A mark that is to be inherited must somehow escape these clearing events, which is why robust mammalian examples are rare and debated.

Clear cases exist in plants and some animals such as worms, and intriguing observations exist in mammals, but the field urges caution. Distinguishing genuine epigenetic transmission from genetic, nutritional, or behavioral effects requires careful, multi-generation experiments.