In the Christmas classic “It’s A Wonderful Life,’’ young lovebirds Mary Hatch and George Bailey pause in front of a dilapidated old Victorian while on a romantic stroll. It’s cobwebbed, creepy, and by all appearances unfit for human life. But Mary sees its potential — and she quietly makes a wish, hoping to live there with George someday. And (spoiler alert!), one day they do move in, and she lovingly scrubs and paints and decorates the drafty old thing until it becomes a home.

In real life, the reverse is often true: Our homes reflect the zigs and zags of our meandering lives until we leave them behind. It happens over time, with swing sets and growth charts penciled on the walls and second floors for unexpected babies. Then, slowly but inevitably, change nibbles away at those foundations. Kids leave. Jobs get transferred. Spouses die. Homes are sold, and strangers move in. The consequences aren’t always heartwarming.

In fact, sometimes they’re downright jolting. Take Kerry Gerbracht, who grew up in New York and came to Boston for college. Her parents built what she calls a “stained-wood beach house’’ in the mid-1980s where she grew up. They sold it 20 years later as empty-nesters, and several people have moved in since. Today, Gerbracht said, “It looks like a circus house.’’

The stained wood has been supplanted by garish oranges, yellows, and mauves, rendering it nearly unrecognizable.

“It’s not my childhood home anymore,’’ Gerbracht said.

The aesthetic changes hurt, because they’re visible reminders that we just can’t go back in time, try as we might.

Once a year, David Sibel of Arlington drives by his childhood home in Framingham, a Cape his father built in the 1960s. The house reminds Sibel of the precious time he spent with his dad as a kid.

“I’d visit and watch him and run around in the empty rooms,’’ Sibel recalled. “It was cool to see it constructed, bit by bit, as a little boy. It wasn’t a huge house, but it was huge to me.’’

His parents unexpectedly sold the home when they moved to Antigua in the mid-1990s.

“I lost the house and to some degree, my parents’ proximity, too,’’ Sibel said. “Like many guys, I used to drive out to Framingham with a new girlfriend and show her where I grew up. Once it was no longer ours, we couldn’t go in. Now I’m tempted to stop in and say, ‘Hey, do you mind if I look around?’ ’’ he said with a laugh.

It’s bittersweet, though. His father had meticulously built a patio, deck, and split-rail fence, and Sibel helped him out. Subsequent owners have changed the look.

“The outside landscaping fell apart. The fence fell down. There’s a monstrous addition on the top floor, not in the right style. I’d cringe when I drove by,’’ he said.

It’s painful to see your past through a car window. Tiffany Marie Spinosa, whose childhood home in the western suburbs was sold after her grandfather died, feels wistful whenever she cruises through the changing neighborhood.

“We drive by now and again,’’ Spinosa said. “From the outside, it looks the same besides the garden. It would have been a lot of upkeep; my grandmother did an amazing job with her garden. I heard years ago they filled in the pool in the backyard, which was hard to hear, since all us neighborhood kids [had] so many memories in it. The houses that have the same families living there all look the same, but anything that’s been sold since 2005 is now a giant house in a neighborhood of Capes,’’ she said.

Melrose’s Tanya O’Hara knows how she feels. On a cross-country trip, she and her brother visited their childhood home in Illinois. While it’s uncomfortable to see a beloved home taken over by new owners, it’s just as bad when the house isn’t even a house anymore. O’Hara’s home is now part of a college campus.

“Our gorgeous Tudor was purchased by a university after we moved and turned into offices,’’ O’Hara said. “It was so sad to go into the bedroom you grew up in and be surrounded by filing cabinets.’’

Now, O’Hara has a painting of the old home hanging in her own house.

I wish I’d had that foresight. My grandparents stayed in their three-story tenement in Lowell until they couldn’t live independently. My grandmother had lived in the house her entire life. When she went to a nursing home with Alzheimer’s disease, she remembered very little, but she repeatedly asked to be returned home, reciting the address by heart. My grandfather stayed in the house alone, even as the neighborhood changed around him. His church up the street closed. The corner salon where my grandmother got her hair done every week shut down, too. Old neighbors moved away. The longtime tenants he rented apartments to grew frail and decamped to nursing homes themselves. The fabric had frayed.

As he was preparing to enter hospice for lung cancer, my mother wondered whether we should move his furniture into storage. There were valuable things, like his mahogany dining room table and grandfather clock, ripe for burglary in a neighborhood that had seen an uptick in crime.

But what if he comes home, we wondered, even though we both knew he wouldn’t.

Still, we left everything intact, decorated for visitors who would never return, a shell of a home surrounded by strangers and flickering street lights, abandoned rooms frozen in time.

My mother and uncle sold the house when he died. The screened-in porch where my grandfather listened to the Red Sox on the radio looks a little weathered. The hedges could use a trim. The only things that remain are trash barrels sitting on the sidewalk, the street number written in big white block letters in my grandfather’s unmistakable Catholic-school hand. I tear up each time I drive by — but I still make that familiar turn up the hill, past the funeral home and the shuttered church and the abandoned parochial school surrounded by weeds, just to see it again.

Homes are our vessels for memories and dreams. They’re brick-and-mortar puzzles of nostalgia, concrete repositories for abstract longing. The squeak of a gate, the creak of a step, the smell of a garden that’s no longer there. They’re the closest thing we have to being able to touch our memories.

There is hope, though. Sibel commiserated with friends about his Framingham house during an informal high school reunion, and one pal had an ingenious idea. Feeling the same nostalgic pangs, he flagged his childhood home on Zillow. When it goes up for sale someday, Sibel’s friend has a plan: He’ll stop into the open house as a pretend buyer for one last glimpse at what was once his.

Kara Baskin can be reached at kcbaskin@-gmail.com. Follow her on Twitter @kcbaskin.