(for the purpose of the examples below, let’s assume all years have 365 days)
a) Odds of a couple sharing the same birthday: 1/365
b) Odds of a couple and their child sharing the same birthday: 1/133,225
c) Odds of a couple and their child sharing the same birthday, and that day being July 19: 1/48,627,125
The article used number “c)” and it probably should’ve used “b)”