Although it’s difficult to pinpoint exactly how much a family costs a city, it’s generally more than single- or child-free citizens. Some city officials argue that it makes more economic sense to prioritise citizens without children, who bring a net economic gain to a city, over families, who bring a net loss. After all, kids don’t make big purchases or pay taxes on their own, and schools can be the biggest expense for local governments.

In the US, closures of public schools are one effect of gentrification. A telling example from Philadelphia is of a technical high school being shuttered and turned into a high-end pop-up restaurant. Likewise, some Finnish cities are shutting down playgrounds so that they don’t have to make the investments needed to meet the latest safety standards.

Accessible housing is also key to enabling families to subsist in cities, yet many bigger cities lack affordable multi-bedroom homes. It’s been estimated that just 5% of market-rate homes for rent in large US cities have at least three bedrooms – and in places such as Los Angeles, most median-earning households can’t afford the multi-bedroom homes available. Even in cities with more family-suitable homes, such as Amsterdam, the properties are often subdivided into individual units for rent to singletons and the child-free (a controversial practice known in Dutch as ‘verkamering’). This is lucrative for developers and landlords, who can earn more from additional housing units squeezed into the same space.

One way that Amsterdam has responded to the space crunch is by building high-rise towers. But Karsten, who has lived in Amsterdam’s Middenmeer neighbourhood with her family for decades, argues that a high-rise is often not very family-friendly. Her research shows that even in Hong Kong, where it’s common for families to live in tall buildings, families complain about these structures, which have less noise insulation and outdoor space than detached homes.

This doesn’t mean that high-rises can never work for families. Some residential towers in Singapore boast kid-friendly play areas and rooftop gardens, suggesting that there’s room to think creatively about different kinds of housing arrangements.

Karsten acknowledges the limited research in this area as well as the difficulties of meeting diverse housing needs within a large city. “It’s very easy actually to build or to provide housing for single adults. They can survive everywhere,” she says, “while it is much more challenging to make neighbourhoods and housing family-friendly and accessible for children.”

Some cities are bucking the trends, however. Vancouver requires a certain proportion of new housing developments to include multi-bedroom units. Rotterdam has been praised for widening pavements and establishing more family-friendly housing. But these policies are far from universal.