My youngest brother and I have birthdays with a difference of 18 months and 14 days. While that’s not a mathematical marvel in any way it’s been interesting in finding pairs of famous people that either share exactly or are close to our birthdays.
The birthday problem asks for the probability that, in a set of n randomly chosen people, at least two will share a birthday. The birthday paradox refers to the counterintuitive fact that only 23 people are needed for that probability to exceed 50%. This isn’t representative of anyone having my exact birthday which is 1 in 365, but also my brothers birthday which is also 1 in 365. Combining those odds (1 in 133,225) and finding a pair of people considered famous or well-known in some way makes the odds out of this world.
Except the odds seem to favor our pairing, and thus the following…
With my birthday being October 14 and my brothers being April 28 there has been one pair that we’ve known for decades and that match us exactly: Joseph Utsler (Oct 14) and Joseph Bruce (April 28).
Since this is a rare scenario it’s quite hard to find another pair of famous/well-known people that exactly match. In finding more there has to be some chronological wiggle room. Thus, a famous pair that allows a 10 day leeway would be Jeannette Charles (Oct 15) and Elizabeth Alexandra Mary (April 21).
A third set hasn’t really been found as of this writing but I feel the odds should be in our favor if two are already easily found.