One is two and three-quarters, the other just a few months old. "They are completely wonderful. Everything people say about grandparenthood is true - it is pleasure without responsibility. It is unquestioned love."
Now that I have a grand-daughter, my thoughts turn to what Christmas treats and outings I can provide. She's a little young, at just fifteen months, for pantomime or most Christmas shows this year. And then again, shows for very young children are usually insufferable for adults to sit through.
I saw a fairly good Bagpuss show a couple of Christmasses ago. Twin girls of eight or nine years were entranced. But their parents spent the whole time on their respective iPhones, or mobiles. Maybe I could't really blame them. But the point of going to theatre with children is to enjoy it through their responses. And anyway, we should all be children in the theatre.
Which makes me feel a bit guilty for not having much liked Goodnight Mister Tom the other afternoon. The children in the audience seemed to like it, though I couldn't be sure, whereas I disliked it - the acting, the script, the child abuse - quite a lot.
I have a big weakness for "cheap" pantomime, that is traditional panto with wobbly scenery, very old jokes, a proper (ie, improper) dame and a raggedy band of three or four musos or, as Ken Dodd says, the Liverpool Philharmonic "after cuts."
And I can see that many children might enjoy that sort of thing a good deal less than I do. That is partly because the standards in children's theatre are generally so high nowadays, not just at places like the Unicorn and the Polka, Wimbledon, but also in the quality of adaptations of the classics such as Winnie the Pooh and Peter Pan.
But it's also to do with the fact that, as adults at Christmas shows, we are seeking some evidence of our pre-lapsarian innocence in the theatre and the world, and a nostalgia for older forms of theatre and music hall. Children don't think like that at all. They are open to all suggestions, and are as easily beguiled by the latest pop song as the corniest knockabout.
The first Christmas show I took my son to, when he was three, was Captain Sooty at the old May Fair theatre. What I most remember about that is a crowd of tiny tots standing in the aisles saluting Sooty on the poop deck while their posh au pairs and yummy mummies sat swathed in furs and cashmere in the stalls.
His next outing was to the Polka, with several pantos around the country thrown in for good measure - in Halifax, Bradford, Birmingham and Manchester - before Starlight Express became the go-to treat for seven-to-nine year-olds all over London. And shortly after that, I think they all went clubbing. No panto nostalgia for them, then.
Re-visiting your own youth is the theme of Sondheim and George Furth's Merrily We Roll Along which opened last night in Maria Friedman's fine production at the Menier Chocolate Factory. I didn't take my son, but I took my younger brother, and we reminisced happily about the British premiere at the Library in Manchester and then again at the old Leicester Haymarket in 1992 (where Maria Friedman appeared in the cast directed by Paul Kerryson) and Michael Grandage's wonderful Donmar Warehouse version for Sam Mendes twelve years ago, which announced the arrival of Julian Ovenden in our musical theatre.
The great thing about Merrily is how it expresses something we all experience: losing the best part of our lives, or the best of friendships, or the unsullied optimism of idealism. People sometimes say that we are living in a golden period of this or that, of new theatre writing, perhaps, or of television comedy (though not if they've seen John Bishop or Michael McIntyre recently).
The truth is that golden periods, by definition, happened in the past. And they probably never happened anyway. It was how we viewed them that defined them as such, a different thing altogether.
But as Sondheim himself says, ruminating on the loss of his partnership with Hal Prince over the troubled first production of Merrily: "We reunited twenty years later for Bounce, but the glory days were over. Nevertheless - I speak for myself, but I suspect Hal would agree - that month of fervent hysterical activity was the most fun that I've ever had on a single show. It was what I had always expected the theatre to be like."