What point is Smiley making by changing the mythology of the story of Lucky Hans through the story?

Variations on the story of Lucky Hans appear several times in the novel, including the version told by Opa to Frank in 1924, Lillian's version remembered by Henry in 1947, and Arthur's tale of Frank and the golden egg in 1952. What point is Smiley making by changing the mythology?

Opa's Hans was rewarded for being charitable. Lillian's story had the same moral but she embellished the reward and made it all the things she loved. In 1952 the story changed and Frank is the hero who bargained for the reward. It was Walter's golden feather that led him to Andy, the love of his life. Family stories change as the times change. The virtue was no longer being charitable but being a good bargainer.