2 easy to nuke lol Rate of fertility (aka the numbers of kids per fertile female) : http://en.wikipedia.org/wiki/File:Countriesbyfertilityrate.svg Now look at the map and tell me that the developed countries which have a high standard of education and a greater HDI have a more kids pe family . Immigrants which (nearly always) come from poorer countries hold on to their traditions until assimilation (a very long process) and keep their traditions when it comes to family . You know that this information is given to people in high school at geography classes . Did you skipped it ?