The comedy Modern Family upends our assumptions about how families are defined in the 21st century. In the 1950s, the American dream was fuelled by the suburban housing boom, and it was understood that a mom, dad and two kids would occupy every bungalow, with one or two cars in every driveway. Conversely, today’s families can be multi-ethnic, gay, and blended, and typically involve adults with working schedules that often exceed the 40-hour work week. Increasingly, as young adults start their own households later and as we live longer, the family home may include adult children and grandparents at the same time.

As the first generation who grew up primarily in the suburbs, with a long commute defining daily life, millennials are charting a different course when it comes to raising their families — and their choices are reshaping our cities. The high costs of driving, coupled with the negative social and environmental impacts of communities designed around the car, is facilitating a generational shift away from the housing choices of the past.

Millennials are seeking neighbourhoods that are walkable, with good schools and parks, and with multiple transportation options. Unthinkable just a generation earlier, they are choosing to forgo driver’s licenses, lawns and spacious suburban living in exchange for the opportunity to walk to school and to work. In the GTA, the most dramatic increases in housing prices are in walkable neighbourhoods, with access to rapid transit. However, these increases are pricing families out of the market.

Our downtown has seen exponential growth over the past 15 years, with a population that has increased from 102,000 to over 200,000 people today, growing four times faster than the city as a whole. Millennials are driving this overall population growth, comprising nearly 60 per cent of our downtown residents.

So what happens when millennials start having kids? Census data shows that parents living downtown are likely to stay put while their children are very young but move out once they reach 5 or 6 years old, often to the suburbs. Too squeezed in a condo, they are pushed out of the city, away from their jobs, in search of cheaper housing. Seventy per cent of recently built or proposed downtown housing comprises either bachelor or one-bedroom units, and the city-wide average size of a resale condo has decreased by 20 per cent in the past 15 years.

Our Official Plan calls for the creation of a variety of housing types to accommodate families. Part of the solution involves securing developments that provide a range of unit sizes and layouts, amenities that accommodate children and youth (such as basketball courts and splash pads instead of pools) — with prices families can afford to pay. Innovative policy tools are required to ensure housing for all. For instance, inclusionary zoning, a policy that requires affordable units as part of all new development projects, has been used with success in other jurisdictions. The City of Toronto, however, awaits regulatory authority from the province to enable inclusionary zoning here.

While the size of condos is one challenge, ensuring a child friendly public realm is another. To this end, I led a roundtable in 2014. We heard that growing families want to live in urban areas. At the same time, they want to be assured that the amenities required for their children to thrive will be available. Affordable condo units with more bedrooms are necessary, but schools, daycares, playgrounds that are integrated into neighbourhoods, and wide sidewalks where children are buffered from cars — matter just as much.

As we integrate new buildings into the older, existing fabric of the city, we need to prioritize the provision of green space and neighbourhood parks. To achieve this, we need to be bold in acquiring the land, setting it aside, and protecting it. Toronto's ravine system provides the chance for children to get their hands dirty — find bugs, play in the leaves, chase butterflies. How else can our new vertical communities better connect with our natural resources?

We need to think carefully about how to better accommodate families in our evolving city. This is why we have begun a new initiative called Growing Up — to invite residents to join in the transformation of Toronto as a place where families and children are offered a high quality of life in dense, urban, green and often vertical settings. If we truly care about ensuring a sustainable future, and reducing our environmental footprint, we’ll prioritize getting this right.

Jennifer Keesmaat is the chief planner of the City of Toronto.