i.g.batten@batten.eu.org wrote:

That's not the only possible interpretation.

It is not necessary to postulate a concept of passing jobs between the
generations. People from different generations may work alongside each
other in the same industry doing entirely different and pretty much
unconnected jobs.

A given industry may have a long association with a particular community
for perfectly understandable reasons - e.g. coal mining in a certain
place because that place is above a coal seam. The coal seam might be
well known for having many centuries worth of useful production in it,
and people in the local area may bring children into the world knowing
that there is no reason not to believe that there will be work for them
in the local area when they grow up. Until someone many miles away takes
a political decision to close the mine down for reasons not connected
with its viability.