Let us try to define the family, not by integrating the numerous factual observations made in different societies nor even by limiting ourselves to the prevailing situation among us, but by building an ideal model of what we have in mind when we use the term family. It would seem that this word serves to designate a social group offering at least three characteristics: (1) it finds its origin in marriage; (2) it consists in husband, wife, and children born out of wedlock, though it can be conceived that other relatives may find their place close to that nuclear group; and (3) the family members are united together by a) legal bonds, b) economic, religious, and other kinds of rights and obligations; c) a precise network of sexual rights and prohibitions, and a varying and diversified amount of psychological feelings such as love, affection, respect, awe, etc.
(p. 266-67)
All these distinctions ... are fantastic at first sight because they cannot be explained on biological or psychological grounds. But, if we keep in mind what has been explained in the preceding section, i.e. that all the marriage prohibitions have as their only purpose to establish mutual dependency between the biological families, or to put it in stronger terms, that marriage rules express the refusal, on the part of society, to admit the exclusive existence of the biological family. (p. 281)
Social life imposes on the consanguinous stocks of mankind an incessant traveling back and forth, and family life is little else than the expression of the need to slacken the pace at the crossroads and to take a chance to rest. But the orders are to keep on marching. And society can no more be said to consist of families than a journey is made of the stopovers which it down into discontinuous states. They are at the same time its condition and its negation. (p.285)