I have posted about connections among cousins before. I believe there is a high degree of consanguinity amongst Cape Cod residents up to about 1880. Cousins marrying cousins was a necessity or at least a common occurance in isolated communities like those on the Cape.
My PAF database has most of the descendants of Richard Sears of Cape Cod and many of those of Thomas Howes. By adding to this collection from the Cape Cod Library of Local History and Genealogy series, the Nickerson Family genealogies, Burgess family, et al I believe I can study these relationships more closely.
From PAF I can export the family number of each individual and whether they are a spouse in another family.
Then I can create a database table of each person in the database and all of their descendants.
Finally I can then count the number of common ancestors shared by each pair of individuals in the database and calculate the distance to the ancestor. For example if the distance to the common ancestor is 2 the ancestor is a grandparent(the two people are first cousins). If the distance to the common ancestor is 1 then the ancestor is a parent (the two people are siblings).
I will generate some preliminary results based on Sears and Howes in my current database and let you know what they look like. I know of many second, third and fourth cousins in these two families that intermarried.