Most americans are descended from people who didn't care enough about family that they were willing to cross the ocean for the good life even though they might never see their family again. (I'm referring to the late 1800 and early 1900s)
The JW biggest problem will be in their "fertile" third world countries and countries made up of people who didn't discend from immigrants.
The people who didn't leave their homeland for the "New World (Americas) were genetically predisposed to make sacrifices to stay with their families because of strong dependence and attachment. These people are NOT going to follow the rules of the Watchtower's cold herritage.