My family class workshop is now entering the payoff phase, as students report on their research projects.
Emily Perrin examined the research on step-families, and noted several flaws. Most studies of families measure how well the family coheres. Step-families usually score poorly on this measure. Emily argued that this is in the nature of step-families. Even high-functioning step-families are likely have looser ties between step-parents and step-children, even if the marriage bond and the (blood) parent-child bonds are solid.
True, it is likely that step-families as a whole are lower functioning than intact families as a whole, tending to more centrifugal than is good for them. Still, I think Perrin makes a good case that researchers on step-families should rethink simply importing a family cohesion measure from research on intact families.