Cultural historians studying gender, family and private life have found that many common assumptions about traditional family structure, a breadwinner father, a homemaker mother, a small nuclear household living apart from extended relatives, actually describe a fairly narrow, historically recent arrangement rather than any kind of universal human pattern. Household structure, gender roles within it and even the very idea of private, domestic life as something separate from public and working life have all varied dramatically across different historical periods and societies.
Extended, multigenerational households and shared working roles were the more common historical pattern
Extended, multigenerational households, several generations and often additional relatives sharing one home, were common across a great many historical periods and societies, considerably more common than the small, standalone nuclear household later treated as the default. Women's economic roles similarly varied hugely by period and social class, working directly alongside men in agrarian and artisan household economies was, for much of history, the actual norm rather than the exception it's sometimes assumed to have always been.
Private, domestic life as a distinct sphere is itself a comparatively recent historical development
The very idea of a private, domestic sphere clearly separated from public and working life is tied closely to specific later historical developments, industrialisation moving paid work out of the household and into separate workplaces, for instance, rather than being a timeless, universal feature of family life. Much earlier historical writing implicitly projected a comparatively recent, largely Western middle-class family model backward as though it had always been the standard arrangement, and correcting that assumption required historians to deliberately seek out sources, wills, parish records, personal letters, that had often been previously overlooked precisely because they concerned domestic and private matters rather than politics or war.
What we're still unsure about
That extended households and shared economic roles were historically common, and that the private-versus-public sphere distinction is itself a comparatively recent development, are well established, extensively documented findings in the cultural history of the family. What's more genuinely a live methodological challenge is that reconstructing genuinely private, largely undocumented domestic life from historical records that mostly weren't created to capture it in the first place is a real, ongoing difficulty, and historians continue to actively debate how much weight to place on the surviving fragmentary evidence versus how much about ordinary people's private lives in most historical periods remains genuinely unrecoverable.
This sits inside Gender, Family & Private Life Through History, one of seven topics in Cultural History, one of seven domains in History, one of seventeen subjects the app can quiz you on.