I teach students the "sociological triad" of race, class, and gender. I have come to add a second triad: age, religion, and region. These factors almost always matter in understanding any social phenomenon.
Later in the term I will have students write their own four-generation sociological narrative, from their grandparents to their (hypothetical) children. I want them to think of their family story in terms of these six standard social forces. In the spirit of leading by example, I wrote such an account of my own family, and gave it to the class to read.
The hardest factor to apply to my narrative was age. At any given moment, age matters quite a bit in shaping one's social circumstances. Over time, especially over generations, though, we move through the various ages, if we are favored with a long life. How to represent the effect of age in an over-time story?
I was seized with a sudden inspiration: how often did the members of my family go through various rites of passage at the customary age? This proved to be a fruitful measure of age-normalcy (or not) for the whole lineage, not just of one or another individual in it. I think this customary-age idea could be turned into a standardized measure of whole family lines.