It must have made my father’s sister very happy when I was born on her 38th birthday in 1926. Sharing a birthday makes a special bond between two people, and she was one of only two aunts I had.

When I was growing up I didn’t know anyone who shared my birth date on April 27th — nor did it occur to me to care whether anyone did. But when I was grown up and my world expanded, I discovered that Joanie, my daughter Deborah’s best high school friend, had been born on my 25th birthday. Later on we exchanged birthday cards (Have a lovely day on OUR birthday). It was surprising to me that Hallmark had even thought to make a card like that.

Some years later I found out that friend Patricia’s husband had been born on my 18th birthday. We four began celebrating our joint birthdays with an annual dinner at the Black Dog Tavern and have kept it going for more than 20 years. The big difference in age doesn’t seem to make a difference. This year I am celebrating old, old age, and David is beginning new old age.

One of us, probably David, found out that April 27 was also the birth date of Ulysses S. Grant. He would be observing his 194th birthday this month, and at every one of our dinner parties we raise a glass to the general.

Recently I made a new Facebook friend from Louisville, Ky. — our connection is that she is filming a documentary about the migration of monarch butterflies. On YouTube she saw the short film I made in 1973 of thousands of monarchs gathering in a tree in Gay Head for the night, and she emailed me to get permission to use it in her film.

As we got more acquainted on email in February and exchanged information about ourselves, I found out she was also born on April 27 — only in 1962, on my 36th birthday. We were more connected than we had thought.

The most amazing discovery I have made concerning mutual birthdays happened a few years ago when I met Sal, a good friend of my friend Phyllis. We discovered that Sal and I not only had been born on the same day, but in the same year, 1926. While I was being born in New York city, he was being born in Providence, R.I. Although we are both turning 90 this month, we manage to get in at least one party together each year.

There is another amazing coincidence in my timeline — Elizabeth, Queen of England, was born in April of 1926, the week before I was. Baby sisters came to both of us in 1929. When she was 21, she married a Navy man, as I did. In 1949 she had a baby boy — so did I. We then each had a daughter in 1951. Then we lost the sequence when I had another girl baby and she had two more baby boys. However, I had a worrisome year when her father died in 1952 — I thought my father would also die that year. But he didn’t die until 1976. The pattern was broken.

Shirley Mayhew lives in West Tisbury.