Hopefully we’ll discover a lot! But we can’t assume we know what we will discover, or how it works.

The reason why people are uncertain about whether trauma can form a genetic imprint is, I believe, that we already know with quite high confidence that maternal stress during pregnancy can cause an epigenetic imprint in the child. So when we find that children of Holocaust survivors have epigenetic changes (note — though statistically significant, they’re also pretty small on an absolute level, but then again the authors didn’t look very broadly), how do we know whether (1) Holocaust survivor mothers are more likely to be stressed during pregnancy (e.g. from PTSD), or (2) there is an intergenerational inheritance of effects of trauma aside from what the mother is experiencing during pregnancy?

Well, we don’t know, at least not until we test these kinds of specific hypotheses. And nobody has yet, as far as I can tell.

Also — the way in which “genes don’t change” hasn’t changed; the genetic sequence is not changed. However, how the genes are regulated can change based on modifications to DNA that does not change the sequence of nucleotides (e.g. methylation). Unlike a change to the genetic sequence, the pattern of methylation is not necessarily inherited because DNA replication doesn’t copy the methylation patterns. Also, the methylation doesn’t alter what proteins get produced (as far as we know), only how much. So it’s an opportunity to include some short-term notes, so to speak, on what components are important. Do those notes reflect a historical trauma that is multiple generations in the past? That, thus far, we don’t know.