On the Baseball Reference website, you can get a listing for each player in baseball history of the ten most similar batters or pitchers based on a statistical formula. For example, the most statistically similar hitters to Babe Ruth are Barry Bonds, Ted Williams, and Lou Gehrig, which probably won't come as a big surprise.
It would be interesting to have similarity scores for other types of famous people. There are personality tests, but we don't have scores for the really interesting people in history. For example, I've always thought that Teddy Roosevelt and Winston Churchill were remarkably similar in personality. (Apparently, they didn't like each other.)
Yet, I wonder whether statements like that are too subjective to be valid. Perhaps it may just seem to me that they were a lot alike because I don't know much about them. If I had known them both close up, would I agree? Or do intimate acquaintances get overwhelmed by small differences and miss the big similarities that are visible from a distance? In general, are personalities too kaleidoscopic for us to form mutually consistent, reasonably valid judgments about them, or not?
Anyway, at least one man knew each of them very well: Teddy's kinsman FDR. Franklin Roosevelt not only was a distant cousin of Teddy Roosevelt, but he married Teddy's niece Eleanor, and held the same job as Teddy had before him: assistant secretary of the Navy. FDR idolized TR, and TR looked fondly upon FDR as a fine young fellow with a lot of potential. TR died when FDR was in his late 30s, so they weren't too far distant in age for FDR to lack a mature appreciation of his hero.
And of course, FDR worked closely with Winston Churchill during WWII, in person, in writing, and on the telephone.
So, here's my question: did FDR think Teddy and Winston were similar? Did he ever express an opinion on the subject? Of course, during the 4 years and 11 months when FDR and WC were peers as President and Prime Minister, FDR was too busy and too sickly to write his memoirs, but did he ever express a judgment on this question to anyone?