Downtown Boston is a cushy place to live, especially for seniors. Someone will take you to the grocery store in a sociable bus. Others will deliver the groceries, flowers and medications. Physical therapy is five minutes away, and so is the hospital, for that matter. Entertainment is close by. And to take advantage of the entertainment, old folks never have to drive, a benefit for aging reflexes. Instead, they can go by foot, by T at 60 cents a ride, or by taxi, paying half-price if they’ve got their senior taxi vouchers.

Organizations like the Harvard Institute for Learning in Retirement, B.U.’s Evergreen Program, Beacon Hill Village and Beacon Hill Seminars provide intellectual stimulation, exercise, companionship and a chance to get out of the house.

With all these advantages for older folks, downtown Boston has become a NORC, or naturally occurring retirement community.

Let’s look at some data. In most downtown neighborhoods the over-60 population is between 16 and 18 percent, about the same as the 40- to 60-year-old population even though, in theory, people in the older group should be dying off. The senior population’s numbers are much greater than the child population, which is about five percent until you hit the over-18 college kids.

The biggest demographic in downtown Boston is, of course, the 20- to 35-year-old age group, the group Mayor Menino targets in his “innovation” district, with its diminutive apartments and trendy work spaces. Almost half of downtown Boston is populated by this group—fancy free, for the most part, unencumbered with children, mortgages and, in some people’s minds, community responsibility.

I have nothing against that age group, since I was once in it. And I’ve got nothing against the growing numbers of old people. My grandfather was one. My parents became old. Now my friends, my husband and even I have little tread left on the tires. You may be old yourself. But I ask you: Are we good for Boston?

The evidence is spotty.

The Boston Foundation recently sounded an alarm about the situation. In its Boston Indicators report this year, this philanthropy identified a possible trend of “an influx of wealthy retirees, decline in public school students.” Such a city, they posit, would price out local workers who would be forced to commute long distances. It wouldn’t be as healthy economically or as appealing.

Such a scenario is easy to imagine given the growth of America’s senior population, which grew 20 percent between 2000 and 2010 and is expected to grow 55 percent in this decade.

Having a lot of seniors brings problems. They aren’t necessarily good for the liveliness of our streets. They patronize restaurants, cultural events, pharmacies and Red Sox games, but don’t really do much for the shops. They already have all the clothing, rugs, bedding and hammers that they need.

They tend to be more politically conservative, although maybe not in Massachusetts. (You’ll notice I consider being conservative to be a detriment to all of us.) Some want parks kept up at the expense of schools. According to Atlantic Cities, a web site run by Atlantic magazine, older people, even in walkable cities like Boston, drive more than do younger people, thus polluting the air and cluttering the streets.

Having a lot of elderly people can contribute to a kind of Balkanization where older folks are holed up together in splendor in a de facto nursing home with the rest of the population on the outside.

Such a cluster exists at the Mandarin Oriental, where someone

will bring you meals, walk your dog and do your laundry. The property tax records for that address do not give people’s ages, but we all can figure out how old property owner Herb Chambers is. Looking at the list of his building mates you find that those you know or whose names you recognize are in their dotage. It’s easy to see that this building is a high-rise Fox Hill with even better services. Many other downtown buildings have similar residents.

There are, however, reasons to be grateful for old folks in the center of Boston. A lot of them are rich. The old folks at the Mandarin Oriental sometimes pay $70,000 or $80,000 annually in property taxes. This goes a long way toward keeping up our streets and sidewalks, and we should thank them. And unless they have tendencies like Bernie Madoff, seniors tend to commit few crimes.

So how can we keep the seniors without becoming increasingly overwhelmed by them?

The answer lies at the other end of the age group. Census figures show that at age 35, a lot of Bostonians leave the city. That’s because they’ve had kids—whose numbers are about the same as the number of people over the age of 85.

Having a lot of seniors in Boston works for me, but only as long as families with kids stay here too. Right now city policies in housing construction and the location and condition of our schools work against families. If we would require builders of housing to incorporate 3 or more bedrooms in their mix, and if we would build more schools downtown, the families and the kids will come. It would be a city everyone will want to live in.