More Darwin- Memes

I want to explore how social memes can impact our human practices.  Dom brought up an interesting though in class; could changing mortality rates of infants impact genetic patterns? If a country has a very high rate of infant mortality (or if we just reference history here- say 1800s or early 1900s) does a link exist between this fact and the amount of children produced?  In today's society many people choose one or two children because they are comfortable with the fact that their children will be healthy enough to live into adulthood.  This then, is a result of human practices changing in regards to medicinal advances, not necessarily genetic or evolutionary components.  What other memes could support this example?  Are there any other human practices that are influenced by changes or advances in modern society, that could be mistaken for adaptive genetic dispositions?  Do you think this is contradictory to the quote Pojman uses that "our behavior is biologically influenced- even determined. So ethical principles and moral theory are little more than rationalizations of genetic programming"?