In terms of the nuclear family graph the number of loops is the minimum number of edges whose removal from the nuclear family graph makes that graph into a tree (i.e. a connected graph with no cycles). The way to break a loop is to make one of the participating individuals a into two people: one person acts as parent and the other acts as child and sibling. In the nuclear family graph this is equivalent to deleting the edge between the two vertices representing nuclear families in which person a is a member.