>>12242122It actually doesn't really need to be epigenetic. Take retinoic acid for example. The fetus will naturally produce a gradient of it from distal to proximal, such that the future hand will have less RA and the shoulder will have more. If the mother ingests RA, it will screw up the development program of the limb.
This is an extreme example, but you can see how stress on the mother can affect development without necessarily changing the genetic and epigenetic code (at least directly)
