I think that sometimes families put 2 and 2 together and get 6, wanting to have a famous ancestor!
It is rather sad when you disprove stories.  I have mentioned this elsewhere, but my mum always assured me that she was descended from a connection of Captain James Cook.  It isn't so.  She may have reached this conclusion because there are Cooks in our ancestry who were mariners, and her own grandfather was a sea captain.  Who knows?
Other very romantic stories seem to be wrong also.  My French ggggrandmother, born in the West Indies, was said to have eloped from a convent aged 17 to marry her dashing adventurer Irish-Dutch husband.  The age is right, but since she married with her guardian's approval, it doesn't sound like an elopement.  Also, her father was said to be a Marquis and Admiral of the Ancien Regime who fled from the French Revolution to the island of Guadeloupe, W Indies.  He seems to have been middle class, a lawyer.  Not sure where the stories came from...
MarieC