Thank you - all this helps. Consider the well-known 'height' example above. No question here but that the genetic contribution is important, but so too are nutrition and absence of disease: look at all these youngsters towering (in purely height terms!) above their parents & grandparents ... But can you help with some examples (or analogies?) from human behaviour (or behavior!)?
In that respect, I have no problem whatever with the generalities, it's the specifics when discussing individuals that I don't understand. For example, "Height is to mining ore, as altruism is to ...?"
I was going to expose my ignorance some more but decided to delete and go back to the books.