Is Your Grandparents Nuclear Family the Same One as Yours?

In general, that's what althuser would call a social formation. It's a social arrangement of relationships that perpetuate themselves through time. And some may be temporary. You might say that a nuclear family does not replicate itself over time. But if you say, the congregation at saint paul's cathedral or something, obviously that's changed for all kinds of dynamic reasons and yet you can still refer to it. Scientific consensus is something like that for coon.