Query on continuity of class across generations

[G*rd*n]

I'm curious if anyone can point me to a reference on the
probability that a child will have the same class or
relative wealth as its parents, especially something on the
Net.  I've read, for instance, that as of 1970, about 80% in
a given income quintile came from a family in that quintile.

Gordon

gcf at panix.com