“It is the consequence of the family’s meeting the collective needs of its members and responding effectively to the demands placed on it by external forces. Thus, it is the product of both internal and external adjustment strategies through which the family achieves a level of fit between its needs and relational resources and the demands placed on it by its environment” (Heath & Orthner, 1999, p. 561).

Heath, T. D., & Orthner, D. K. (1999). Stress and adaptation among male and female single parents. Journal of Family Issues, 20, 557-587.