Prince George might have two but how many of today's children are fortunate enough to have even one great-grandparent on the scene? It's a question that is difficult to find a definitive answer to - no-one appears to collate this information for the UK.
My unashamedly unscientific straw poll of friends and colleagues however suggests that the royals are now relatively unusual in having four generations around at once. We might be seeing unprecedented life expectancies but later parenthood seems to at least cancel this out.
My eight-year-old son, Luca, is blessed with a great-grandma, Doris, who's now 92. Over the years we've come to appreciate ever more how fortunate we are to remain a four generation family. For my son and my grandma's three other great-grandchildren (the oldest is 13), she's something of a treat, whilst for her, it's pretty amazing to be around to witness her grandchildren all grown-up and having children themselves.
As Luca puts it, 'all my grandparents [he has three of the standard variety – all great in the other sense of the word though!] are special and nice but having a great-grandma is extra special, a bonus.'
He loves visiting her and having a game of Scrabble, a good old chat about 'the olden days', or chasing alongside her mobility scooter (which he thinks is uber-cool and fancies a go on - I've told him he can have one of his own for Christmas in about 80 years' time).
The thing about great-grandparents is that they are like grandparents, but even more so. They're even older, and therefore even more intriguing, possbily exotic, to children. They're also an enlightening link to another era: when my son studies World War Two later this term at school, you can guess who he'll be calling upon to hear a first hand account. He's already fascinated by her tales of childhood in the late 1920s; how when she was his age there was barely a car on the road and certainly not a TV in sight.
This echoes the experience of, Joel Carlowe, now 13, who remembers how his great-grandpa, Michael, brought history alive for him, (he died when Joel was 10). "He had many fascinating stories about his time during the war. His amazing tales weren't always about fighting. Some were just inspirational. He was a great person, like a 'living fossil'."
Jo, now in her 30s, recalls her great-granny's generosity with much affection. "I had a great-grandma we called Greaty. She used to save 20 pence pieces in little painted pig money boxes for my brother and me. We used to love going to see her to collect them and would spend most of our time in her flat counting them all up whilst Mum and Dad drank tea. She wasn't wealthy so it must have been a big thing for her to do this. I was given the money box when she died and still cherish it."
Katherine, 40, had two great-grannies when she was little. "One died when I was about seven," she says. "I still have some lovely memories of time spent with her (having a bath in the tin bath in front of the fire and feeding the chickens)." She also enjoyed her stories of bringing up three boys in a one-bed cottage between the wars – another thing great-grandparents surely bring to the table, along with a pot of tea and a plate of chocolate bourbons, is a sense of perspective on how we're mostly quite fortunate today with our relatively comfortable lives. Call it the 'you don't know how lucky you are factor'.
Not all great-grandparents are or were as benevolent. The frustrations of ageing, failing bodies and minds and having been part of a 'children should be seen and not heard' culture could surely make anyone cantankerous and even slightly scary, as another former great-grandchild, Emma, says.
"I was terrified of my great-grandmother as a child - I felt like we were viewed as a nuisance and the slightest sound we made would annoy her! I think she was only in her eighties but she seemed to us as if she was about 130!"
Katherine had a similar experience with her other great-grandmother, who died when Katherine was about 14. "She called my brother 'it' and regularly hit him with her walking stick!"
All in though, even if they're whacking the little ones with their stick (thankfully ours doesn't) or bellowing that they can't hear you (yet complaining the children are too noisy when they're whispering), to coin those classic 1980 song lyrics, there's no one quite like a great-grandma and we'll be forever grateful that we've had one in our family.
Have your children got any great-grandparents?
What does it mean to them and you to have great-grandparents in the family?