I have 21 first cousins, a brother and a sister. This means that, including me, my generation (the children of my parents, and their brothers and sisters) consists of 24 people. What do you think about that? Does it strike you as a big number, as a Goldilocks number (just right) or rather on the low side? One of my friends at university, one of the first people I ever befriended who had four English grandparents, believed it was a large number, and made a reference to Big Irish Families. He had a sister and just three first cousins.

Some of the kids I grew up with here in West London had 70 (yes, seventy, count them) first cousins and six siblings, so our family numbers didn’t seem especially big. My own children (a boy and a girl) have five first cousins, making for a generation of just seven children between me and my wife, her brother, her sister, my brother and my sister. (I was going to write “her brother and sister” and “my brother and sister” there, but I don’t want you to get the wrong idea.)

My generation, the 24 people recorded in the opening paragraph, consisted of 15 women and 9 men. Two of my first cousins (one male, one female) are dead. My oldest cousin was born in 1948 and, all being well, will turn 70 later this month. Until then I can summarize our ages with the same numbers as the decades in the last century when we were born. We are, collectively, in our 40s, 50s and 60s, and were born in the 40s, 50s and 60s. My youngest cousin was born in 1969 (less than 40 days before the beginning of the 1970s) so she will not turn 50 for another 20 months or so. She is the only one of my cousins still in their 40s. The gap between the oldest and youngest members of my generation is a few months short of 22 years.

The next generation, incorporating the children of my first cousins, and my nieces and nephews, and my own children, began in 1973. One of my cousins had a son when she was 18, younger than my parents or any of my aunts and uncles were when they became parents. That boy died in 1991. The youngest of this new generation is my own daughter, born in 2006. The gap between the oldest and youngest members of her generation is over 33 years.

One of my first cousins became a grandmother shortly before my daughter was born, so my children’s generation and the next one are overlapping. If my children become parents, and leave it as late as I did, then my grandchildren’s generation, incorporating all the descendants of my first cousins, will span over 50 years. It could well overlap two other generations.

I can name all of the children born to my first cousins – my first cousins once removed – and know the years (if not the exact dates) they were born, but I do not yet know these details for their children. I wasn’t even sure what that family relationship is called until looking it up just now. It’s “first cousin twice removed”. There should be time enough to get to know about them in the years ahead, but the following statement will only be true for a few more days: my cousins, my siblings and I are, collectively, in our 40s, 50s and 60s, and we were born in the 40s, 50s and 60s.