Strange coincidence

white and blue floral table lamp


My mother’s birthday was the 15th of October. My good friend, the late Michael Jacobs, a fine author, was also born on that day, but many years later. Michael’s mother, the late Maria-Grazia, was born on the 8th of May. I was born on the same day, but many years later.

The chance of two people sharing the same birthday is quite small. It is 1 in 365 or 0.0028. Things get more interesting when one considers a group of people. In a room of 23 people, the chances that two people share a birthday is 0.5 or 50%, and when there are 75 people the probability increases to 0.99 or 99% (see: and  

I have no idea how to calculate the probability that my mother and my good friend share the same birthday AS WELL AS his mother and me sharing the same birthday. It is too long since I studied statistics and probability at school!Even then, I doubt I could have worked it out.



Photo by fotografierende on

2 thoughts on “Strange coincidence

  1. I have been celebrating my birthday for 64 years, during 63 of which I didn’t know a single person with the same birth-date (a primary school friend was two days before and that was the closest I knew of to mine). Four days before this year’s birthday I met a woman who volunteers for my husband’s charity, Plan Zheroes, and we discovered that we shared the same birthday although she is a few years younger. Then on my birthday I discovered through Facebook that a woman I became friendly with on our recent tour of North Korea ALSO has the same birthday but is a couple of years older. What are the odds of all three of us having the same birth-date, I wonder?!

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