We frequently hear the term “values” discussed with regard to American politics, culture and life. But what are "American values," exactly? All week, we’re delving into this question. Yesterday, we discussed reinvention. And today, we’re looking at family: how we came to use the terms “family values” and “American values” interchangeably, and the moving target of what Americans actually consider a family.

Brian Powell is a sociology professor at Indiana University and author of “Counted Out: Same-Sex Relations and Americans' Definitions of Family," published by the Russell Sage Foundation. He’s spent the past seven years surveying Americans on what they think constitutes a family.