The recent furore over a photograph of a little Asian boy peeing in a rubbish bin in a shopping mall in Richmond, a satellite city of Vancouver, echoed stinks that have periodically erupted in Hong Kong and elsewhere. Prompted by responses to the incident on social media - the picture, taken on a smartphone, first appeared on Twitter - national news channels here picked up the story, such as it was. And to a surprising number it seemed cut and dried that the child in the photo, and the woman steadying him, must be of mainland Chinese origin - although, in fact, all that could be gleaned from it was that they were ethnically Asian.

That one image sparked the type of heated discussion with which you may already be fami-liar. Similar stories in Hong Kong this year and last provoked condemnation of "mainland manners", feeding a burgeoning prejudice that has likewise been fuelled by reports of the uncouth behaviour of mainland Chinese tourists in Paris, Seoul and various other parts of the globe. One wealthy visitor to Milan, for example, when asked to extinguish her cigarette in a luxury Italian boutique, apparently replied that she would buy 20 purses if only she were allowed to smoke in the store.

The Canadian story played out something like this: some online commenters were happy to decry the impropriety as typical of "Chinese" or "Asians" in general, while others wondered whether the woman belonged to an older generation of Chinese immigrants, or came from a rural part of China. As in Hong Kong, the nuances did seem to matter in Richmond, which is, after all, North America's most Chinese municipality - and many local ethnic Chinese, perhaps with Hong Kong connections, were quick to throw the "mainland" accusation out there.

Queenie Choo, the head of Success, an immigrant-services organisation in Vancouver, insisted, however, that she had never seen public peeing on her travels throughout China. Another local Twitter user commented: "I've seen tons of Caucasian adults peeing everywhere."

To Canadians unfamiliar with gripes about the behaviour of mainlanders, the extent of the uproar may have been baffling, but it appears also to have served another purpose here - the row has led to a debate over the emerging North American movement towards so-called "elimination communication", whereby parents read cues from their child as to when they need to relieve themselves. No need for nappies.

Cultural differences, parenting practices … whatever the issue, the explanation behind the little boy peeing in a bin might, after all, have been simple: sometimes, when you gotta go, you gotta go.