Thanks for the informative post- I would like to add another layer which you most already know about but as it is my wife's research topic I'm too excited to skip it:
Epigenetics - epigenetic is a layer that's sits on top of the genetic material, the thing that determine how we will look, will we be healthy or sick (to some extent) and so on - those are tiny molecules that are connected to our DNA and(generally speaking) prevent access to the mechanism responsible to the transformation of DNA to proteins, and proteins are a main part of our body - a problem with a protein or two can harm a person seriously.
Now - interestingly - epigenetic CAN be inherited(the mechanism is controversial) but they are also changing due to lifestyle deeds - smoking for example can result in harmful epigenetical changes.

This is short, and lacks bibliography- but I couldn't hold myself!