I'd be interested in reading that study. My family would seem to be an exception, based on my family history research. When my paternal ancestors first came to London from Cornwall, they seem to have become successful merchants, from whence they became minor gentry in the Tudor/Stuart period, then back down to tradespeople by the 18th/19th century, and in the 20th century, my grandfather was a bus conductor and my father a teacher. So we seem to have been up and down the class hierarchy quite a bit.