I was sitting in the Natural History Museum -- or the "Dead Zoo", as Joyce called it -- last Sunday, and I was not alone.
Half of Dublin's dads had apparently also been told to take the kids off somewhere while the mums got to grips with the Yorkshire pud.
I was chatting to a friend I had bumped into and basking in the sense of reflected glory you get when your child is well-behaved in the presence of strangers.
My daughter had made a friend, a little boy, and the pair were showing each other their favourite stuffed animals.
How well-adjusted she is, I thought. How friendly and popular. So popular, in fact, that when it was time to leave, this young man refused to let go of my daughter's hand.
"He's very friendly," I said to his mother.
"And very determined," she replied as she tried some sort of martial arts move on his arm.
"Dad," my daughter said excitedly as we passed a family of stuffed gannets, "do you know what that boy said to me?"
"He wanted me to come home with him and be his sister." She giggled at the idea, but I could see it had some appeal for her.
Something twangs at the heartstrings when an only child mentions anything to do with siblings.
I looked about at the glass cases. Preserved birds fed their chicks. Mothers nursed their litters. Mammals suckled their young. Even stuffed animals have more than one offspring, I thought.
Yes, I have read about all the studies that show only children are happier and do better than children who have brothers and sisters.
And yes, I read the interviews with three happy, healthy "onlies" in this newspaper earlier in the week.
Yet I can't help believing that kids are better off in the knock-about, rough-and-tumble world of a big family.
There is a nagging guilt associated with being the parent of an only child. Wouldn't she be happier with a brother or sister? Wouldn't we?
Somehow, it wasn't to be. In fact, we were very lucky to have one. More would have been nice, but we are thankful for our good fortune. Yet sometimes, it feels like a failure.
My daughter soon forgot her invitation to be part of a bigger family, but it got me thinking. I know, I thought. Let's get a dog.
Great idea, said our friends. They're great companions for only children. Our little girl liked the idea too. "Let's call her Snowflake!" she said.
Although dogs in the abstract appealed to her, actual flesh and blood dogs were another matter.
My brother's dog, a hulking great chocolate labrador who could knock her over with a swish of his tail, sent her clinging to my leg for protection.
But I soon discovered that, when both she and dog had calmed down, they got along very well.
After a while, she was petting him and holding her hand out to be licked.
I thought back to my own boyhood, and my companion, a back and white cocker spaniel called Paddy.
Then there was Homer, a dim-witted golden labrador. And Buster, a manic mutt with a nasty nip.
I remembered the nice feeling of having a licky welcome when you came down first thing in the morning. And later having your arm pulled out of its socket when the dog took you for a walk.
We were not short of advice. Westies are great with kids, said one friend. Poodles said another. Spaniels are too lively; thoroughbreds get sick; you won't have a stick of furniture left.
Get a mongrel from the pound said a doggy friend. It seemed good advice. They are healthier, have better temperaments, and they're cheaper.
In the DSPCA shelter, she set her heart on Pipsi, a 10-week-old terrier cross puppy. She wriggled with pleasure when Pipsi licked her cheek. I signed the papers.
By the time you read this, our new dog will have arrived. There will be pee on the floor and teeth marks on footware of all kinds.
But, in a strange way, our family will feel more complete.