What is a family? Simple question, right?
From biological point of view, I would say male, female and their offsprings. (can be applied also on animals), this is the smallest unit. But are children important in this definition?
From sociological point of view, it's much more complex. We must extend biological definition with foster parents (one or both), in case the kid doesn't have parents and behave very badly, it can have more pairs of foster parents, but this I would classify as more families. Now one parent dies - this is also assumed a family. When both parent die and only children are left, this is also assumed family.
Now from genealogical point of view - can we all of previously mentioned (and other variations) classify as family? Or are genealogists interested only in biological bonds / relations?