Comment by chao-

Personal context: I am an American of European descent, with most of my ancestors having arrived between 1880 and 1950 (pretty solidly "Western"). Extended family is broadly well-off enough to not be financially in need in retirement.

Observation: Sooner or later, all of our family's elders have wound up cared for by a mix of children, grandchildren, nieces, and nephews. Even those who didn't have children. We're an ornery bunch, so quite a few stubbornly insisted they didn't need anyone, yet eventually they did. Care often came at an inconvenience to those providing it, but one way or another, in one form or another, care was given. I can only think of one person from my extended family who wasn't cared for by the younger generations in his final years.

Speculation: The average number of children in my extended family hovers around three, and most of us are in a few geographic clusters (not the same city, but still a cluster). Perhaps if the average litter was between one and two, and/or we were more spread apart, we may have slipped into line with that stereotype?