A recurring feature of family history is surely 'Titanic Maid' syndrome: by which I mean the family legend, recounted in all sincerity, of the relative who travelled on the Titanic and perished along with so many others on the fateful night. It makes for a great story, except that further enquiry reveals that there is no truth in it all ... No one has ever taken the time to examine the facts, such as they can be established, and so the yarn is wheeled out over time and unwittingly recycled. I actually had a beneficiary recount this very story whilst working on a case for Title Research, and in various guises the syndrome recurs so frequently that it seems to me almost to constitute an urban myth; some folklorist should certainly be collecting and studying this material. Needless to say that in the case I mention the 'maid' in question turned out to be alive in 1916 and - I couldn't resist looking - she did not even appear to feature on the Titanic's passenger list(s).
Another variation popped up in a recent case: the surname - Peto; the story - the Petos were of Mediterranean origin, and true to the passionate nature of the peoples of that region the particular individual under consideration was described as highly-strung, capricious and wilful. Another fine story, except that further enquiry established that the ancestor in question - one Priscilla Peto - was born in Bermondsey. Now maybe Priscilla was indeed a handful, and there is no doubt that Peto is an unusual sounding surname; maybe somewhere there is even a grain of truth in the story, but if so it must pre-date Priscilla's birth in 1864; but even in the early nineteenth century the Peto family seem to have originated from Wallingford in Berkshire - not known for its olive oil and wine, as far as I know.
I don't doubt the sincerity with which these stories are told, but it is interesting to speculate why this phenomenon occurs. Perhaps people need something to distinguish their family, by endowing them with some unusual attributes or attaching them to some famous/infamous event. The latter certainly offers a frisson, as anyone who has ever discovered that a relative died on the Somme, for example, will confirm.