I grew up with a mother whose birthday was the day before mine.\u00a0 It was always just one of those things, and in a family of 5 children very close in age one of the things that made me feel a little different.\u00a0 In terms of close relations, my mother\u2019s birthday is the closest to my birthday.\u00a0 However, when this theme came up, I already knew that I had at least one ancestor not so close whose birthday was the same day as mine since I had noticed it in my database.\u00a0 I thought I would look to see if there were any others, just to know this factoid.\u00a0 I figured out how to get my database to filter all the people by that date, and discovered that there are actually 6 people with the same month and date of birth as mine.\u00a0 None in the same year though.<\/p>\n
Next I figured out the relationship with me for each of these ancestors.\u00a0 It ranges from second cousin once removed (the closest) to a first cousin 5 times removed.\u00a0 There are also a couple of third cousins at one or two removes.\u00a0 The second cousin once removed was also closest in terms of the year he was born, being only sixteen years older.<\/p>\n
The birthday problem or birthday paradox is a standard problem in probability theory.\u00a0 You may have heard that in a room with 23 people the likelihood of two people sharing the same birthday is about 50%.\u00a0 This assumes some things the people in the room were randomly chosen, like birthdays falling equally on any given day, and does not take leap years into account (the individuals born on February 29).\u00a0 For the question of likelihood that someone else\u2019s birthday falls on my birthday, the odds are different.\u00a0 My birthday specifies a month and date.\u00a0 This changes the formula.\u00a0 For a greater than 50% chance that one person in a roomful of people has the same birthday as you<\/i>, there would need to be at least 253 people.\u00a0 This article<\/a> explains more than I wanted to know about the question.\u00a0 Since my genealogy database currently has 3231 people in it, it makes some sense that there should be at least a couple who share the same date of birth as mine.\u00a0 Not everyone in my database has a birth date entered, some have nothing and some have a partial entry (year, approximate year, sometimes a month as well without a date).\u00a0 So the pool of people I can compare to is smaller than the total.<\/p>\n Knowing that I have 5 matches, I was curious about my siblings so I ran the same sort for each of them.\u00a0 We were all born in different months.\u00a0 My sister, born in February, had 8 exact matches.\u00a0 My brother born in March had 4, my brother born in November had 6 and my brother born in October had 3.\u00a0 I don\u2019t know what this means in any statistical way – likely nothing – but I think it is interesting.<\/p>\n","protected":false},"excerpt":{"rendered":" I grew up with a mother whose birthday was the day before mine.\u00a0 It was always just one of those things, and in a family of 5 children very close in age one of the things that made me feel …<\/p>\n