The word family is used to refer to a variety of relationships ranging from two persons living together to the entire human family.
More precision is needed when public policy depends upon how a family is defined.
Societies have come and gone, but childrearing families of some kind have endured throughout the ages. The integrity of every society ultimately depends upon the competent parenting of children in family units, but questions about how that should take place arise periodically. This concept has been employed primarily to signify a heterosexual, conjugal, nuclear, domestic unit, ideally one with one male primary breadwinner and a female primary homemaker and their dependent offspring. This unitary, normative definition of legitimate domestic arrangements is what my book defines as ephemeral with little regrets, because of the race, class, gender, and sexual diversity it has occluded and the inequities it has exacerbated. There is no question that families can spawn racism, sexism, and social inequities.