What are the odds of siblings having the same birthdate, different months, but same date, like the 14th.?

Question

Let me clarify: I am the oldest and I was born on August 14. Four years later, my sister was born on April 14. Six years after her, my second sister was born on July 14.

Answer 1

Assuming their births are independent events the chance is 1/365 (well actually more like 1 in 365.2425, but let's ignore leap years for a moment).

The reason is that you can just imagine that the older child's day is already set. Let's say October 5th. For the second child to match, there is only 1 day (Oct. 5th) out of 365 (days in a year) that will also match.

Edit: Correction, I indeed did misread the question. If you only care about the number (not the month), then it is closer to 12/365 or nominally 1/30.

Answer 2

Surely it's 1/30? If you're asking the chances of having a child on the 14th October, then two years later having a child on the 14th August, the odds of having two children whose birthdate was the 14th would be 1/30 because there are an average of 30 days a month? (Obviously that's not an exact average, that's just my guess taking into consideration February and the months with 31 days). The odds of having two children with the birthdate specifically of 14th October for example would be 1/365 as the above person says.

Answer 3

For 1-28, odds are 12/365 for non leap year, 12/366 for leap year
For 29 odds are 11/365 for non leap year, 12/366 for leap year
For 30 odds are 11/365 for non leap year, 11/366 for leap year
For 31 odds are 7/365 for non leap year, 7/366 for leap year

Of course for twins, triplets, etc, the odds greatly increase!

Answer 4

"Puzzling" is way off. He probably thought you meant, the same exact date (like April 14th)

The actual odds are about 1 in 30.

Answer 5

i don't know but i have cousins that are brothers that both have the same birthday and they are 3 years apart.