When it comes to forebears of recent memory... well, forbearance may be the best watchword.
But for the more distant in time, even if their story may be distasteful, I'd rather tell it. It's history, and I'd rather relate it as truthfully as I can.
We've known for some time, in my immediate family, that we're descended from the brutal and racist whaling captain Howes Norris of Martha's Vineyard -- nominally civilized on land, it seems, but murderous at sea; his story is told in historian Joan Druett's "In the Wake of Madness". (It's conceivable, Druett implies, that the tale of Norris's last voyage and his murder by members of his crew may have reached the ears of Herman Melville, and had some influence on the creation of the character of Ahab.) There is no comfort in tracing one's lineage back to someone like that. But I see little to be gained by ignoring -- or worse, whitewashing -- the facts of his grotesque abuse of his crew... including the prolonged torment, and eventual death, inflicted by the captain on a steward who is thought to have been a runaway slave.
Genealogical research, and the creation of meaningful profiles from the best sources I can find, generally gives me joy. I couldn't make that claim in the case of Howes Norris: it is literally disturbing to me to think that I carry the man's DNA. (And there is, in addition, a sadness associated with knowing the tragic story of his wife Elwina, who died nine years after Howes in a bizarre incident when a lightning-bolt shot down the chimney of her house, into her livingroom; and that of a son who later died when his ship caught fire at sea: truly, a family that lived under some strange, dark cloud.) But in my mind I hear Shakespeare's words, spoken by the dying Hamlet to Horatio: "Report me and my cause aright/To the unsatisfied." That charge needs to be followed, I think, even when the "cause" may not be worthy, ennobling, or attractive.