My 2ct’s worth-Perhaps the equal sharing in the younger subset is due to having siblings at home and parents who reprimand them when they fight over toys and goodies?
I’ll add 2 more: The nuclear family tends to be socialistic, even communistic. Which is fine for a group of people related by blood and who reciprocate unconditional love toward each other. But that relationship doesn’t translate upward into anything bigger than a family group. Not even a tribe, and certainly not a nation. Liberals either don’t understand this, or they desperately wish it were so (perhaps because they were missing something in their own family lives, so try to force the society to make up for it writ large).