Exactly how does a genealogist define “family”? Is it two parents and 2.5 children? Is it every person related by blood, marriage and adoption for generations?
The Japanese trace their families in terms of the head of household, regardless of bloodline. Japan is a patrilineal society and each family household is registered with the local government through a document called a koseki. The head of household is typically the eldest son, or chounan. If there is no chounan, such as in a family with only daughters, the eldest girl will often marry a second (or third, fourth, etc.) son who then is adopted into the family, taking on the role of eldest son and changing his surname to that of his wife. In a traditional agrarian society, this was a functional way to pass on property, generally the family farm and cemetery. But what if the sons did not want to want to maintain the family farm? Again, adoption was in order. And those sons who chose this path? They were removed from the family register, not exactly disowned, but no longer recognized by the local government as “family”, thereby creating a genealogical conundrum. How does a genealogist process this information? Which line is then researched? The bloodline (which is no longer considered family)? Or the head of household line? Gotta love the Japanese for everything except genealogy. How does a researcher choose to go about this?