I wonder if the rise of 'psycho-babble' from 1965 thru 1980 is the main driver here. The changing socio-economic landscape, coupled with increased geographical mobility, surely disrupted family structures at least as much as the 'input' that Mum and Dad may or may not have been listening to. With chaged structures and separation by physical distance, families became predominantly insular, tiny islands, sealed boxes with two adults and 2.4 children (the old joke). In place of shared cuture with grandparents and aunts and uncles and perhaps older 'peers', each unit was 'on its own'. And with that comes the collapse of the transfer of social capital ... its the transfer of social capital as it related to raising kidz that got lost.... Similarly, the simple influence of the past mediated through an older generation disappeared, along with regular contact with living examples of 'a better way'.

Just my 2d/2c

JPM
The plural of anecdote is not evidence.