Ours come in clusters. In one month on the 18th, my maternal grandmother, the 23rd my great aunt and my younger son, then 2 days later me. Other close groupings in one week like that through the year but no others on the same day, nor can I see any on the wider tree.
Due to reasons I won't bore you all with, several months before my son's birth the operating theatre was booked for his arrival, and I was able to go out and phone my great aunt to tell her "Guess what you are getting for your 89th birthday?" The following year his first and her 90th managed a joint message on the radio.